Journal articles: 'Magneto-optic Kerr Effect (MOKE)'

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Zhang, Kai, Yuelei Zhao, Zhiqin Chu, and Yan Zhou. "Event-based vision in magneto-optic Kerr effect microscopy." AIP Advances 12, no. 9 (September 1, 2022): 095315. http://dx.doi.org/10.1063/5.0090714.

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Magneto-optic Kerr effect (MOKE) microscopy is a widely used technique for observation and characterization of microscopic magnetic structures. While being efficient and easy-to-use, current commercial MOKE microscopes are not superb in time resolution, limited by the frame rate of the camera. Here, we introduce a revolutionary sensor, namely, the event camera, as a convenient add-on to traditional MOKE microscopy and explore the potential applications of event-based vision in research areas using MOKE microscopy. We use the frame stacking method to improve visibility to human eyes in generated slow motion videos. We perform a proof-of-principle feedback control experiment using the event-based vision data and characterize the overall latency of the feedback loop as short as 25 ms with our current prototype. Finally, we discuss the limitations of current event cameras in MOKE microscopy as well.

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Nurrahman, Mohamad Reza, Dongha Kim, Min-Kyo Seo, and Alexander A. Iskandar. "Enhancement of Magneto-optic Kerr effect of YIG nanoparticle by backscattering suppression." Journal of Nonlinear Optical Physics & Materials 28, no. 04 (December 2019): 1950043. http://dx.doi.org/10.1142/s0218863519500437.

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Magneto-optic Kerr effect (MOKE) enhancement is studied for Yttrium Iron Garnet (YIG) nanoparticle. The MOKE is quantified by the ratio of the polarization components of reflected wave, namely between the perpendicular component to the parallel component with respect to the polarization of the incident wave. Thus, the enhancement of MOKE can be obtained by increasing the perpendicular component or reducing the parallel component of the reflected wave polarization. An FDTD calculation is performed to obtain the scattered field. Projecting the resulting scattered field to the vector spherical harmonic basis, we show through multipole moments analysis that the suppression of backscattering non-MO field and the raise of the backscattered MO field can be achieved by subtle superposition of some optical modes. For the specific YIG particle system and the wavelength range chosen, the result shows that enhancement of MOKE up to 7.5[Formula: see text]mrad can be achieved.

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Sun, Yiming, Liangwei Wu, Mengmeng Yang, Mengjia Xia, Wei Gao, Dongxiang Luo, Nengjie Huo, and Jingbo Li. "Anomalous Hall Effect and Magneto-Optic Kerr Effect in Pt/Co/Pt Heterostructure." Magnetochemistry 8, no. 5 (May 12, 2022): 56. http://dx.doi.org/10.3390/magnetochemistry8050056.

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Magnetic multilayer with large perpendicular magnetic anisotropy (PMA) has attracted sustained interest owing to its importance to fundamental physics and applications. In this work, the high quality of Pt/Co/Pt heterostructures with large PMA was successfully achieved to exhibit a large anomalous Hall effect (AHE) with squared Hall loops. By calculating the proportional relationship between the longitudinal resistivity (ρxx) and the abnormal Hall coefficient (Rs), it is confirmed that the basic mechanism of AHE comes from the external skew scattering (SS) and side jump (SJ), while SS contribution, related to asymmetric scattering from impurities, is dominant in the AHE. Furthermore, the obvious magneto-optical Kerr effect (MOKE) was also observed using the polar MOKE microscopy. The obviously circular magnetic domain can form and propagate in response to the applied out-of-plane magnetic field, resulting in the magnetization reversal of the entire film. This work offers important information in terms of both AHE and MOKE in the ultrathin ferromagnetic films with perpendicular anisotropy, establishing the application foundation for the nonvolatile memories and spintronics.

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Panda, Janmey J., Krishna R. Sahoo, Aparna Praturi, Ashique Lal, Nirmal K. Viswanathan, Tharangattu N. Narayanan, and G. Rajalakshmi. "High-sensitivity characterization of ultra-thin atomic layers using spin-Hall effect of light." Journal of Applied Physics 132, no. 7 (August 21, 2022): 075302. http://dx.doi.org/10.1063/5.0102355.

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The fast-emerging diverse applications using a variety of magnetic/non-magnetic heterostructure ultra-thin films warrant the sensitive characterization of the electrical, optical, and magnetic properties of the interface. As a practical alternate to the conventional magneto-optic Kerr effect (MOKE) method, we propose and demonstrate the spin-Hall effect of the light (SHEL)-based MOKE method with competitive sensitivity and scope for further improvement. The SHEL-MOKE technique is a versatile surface characterization tool for studying materials’ magnetic and dielectric ordering, which are extracted from the variations to the phase-polarization characteristics of a focused beam of light reflected at the interface, as a function of the applied magnetic field. Using this technique, we measure the magnetic field dependent complex Kerr angle and the coercivity in ultra-thin films of permalloy (Py) and at molybdenum disulfide (MoS[Formula: see text])—permalloy (MSPy) hetero-structure interfaces. A comprehensive theoretical model and simulation data are provided to strengthen the potential of this simple non-invasive optical method. The theoretical model is subsequently applied to extract the optical conductivity of non-magnetic ultra-thin layers of MoS[Formula: see text].

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Boukhalfa, Radhia. "The Study of Magnetic Properties of Fe/Ag/Cr Thin Films." Diffusion Foundations 18 (September 2018): 1–6. http://dx.doi.org/10.4028/www.scientific.net/df.18.1.

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(300Å)Fe films were deposited, on MgO (001) single crystalline substrate with various buffer layer thickness tAg (Å) / (75Å) Cr. The magnetic properties of the Fe films were measured by magneto-optic Kerr effect (MOKE) technique. The MOKE measurements provided the tAg buffer layer thickness dependence of the hysteresis loops and the change of loop shapes with the surface roughness. It was found that the magnetization reversal process changed with the surface roughness. Magnetization rotation dominated the magnetization reversal for the smoothest films. As the films roughened, the domain-wall pinning set in, eventually dominating the magnetization reversal for the roughest films. Additionally, the magnetic uniaxial anisotropy in the Fe films disappeared as the roughness parameters increased. It was also found from MOKE that the surface roughness strongly affected the coercivity.

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Shang, Xue Fu, Ya Wei Wang, and Ming Qiu Tan. "Full-Potential Study of the Magneto-Optical Kerr Effect for AuMnSb and AuMnSn." Advanced Materials Research 750-752 (August 2013): 941–45. http://dx.doi.org/10.4028/www.scientific.net/amr.750-752.941.

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The magneto-optical Kerr effect (MOKE) for both Heusler type alloys (AuMnSb and AuMnSn) were studied using the full-potential linearized augmented plane-wave (FP-LAPW) method, based on the density functional theory implemented in the WIEN2k code. The differences with previous calculations on the Kerr spectra have been found explicitly. At proper Lorentzian such asδ= 0.4 eV, the calculated Kerr angle of AuMnSn reaches its maxima +0.3° near 0.6 eV and-0.5° at 5.2 eV, respectively while the MOKE spectra of AuMnSb exhibit less prominent Peaks (+0.5° at 0.3 eV, -1.9° at 0.9 eV, -1.0° at 2.4 eV and-2.0° at 5.3 eV). The results on the spectra in this work showed quite a lot differences with all previous all-electron calculations. It is concluded that the contribution from Sb (or Sn) site to the magneto-optical kerr effect is quite crucial in Heuslar alloys.

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Li, Qian-Yang, Shuai-Jie Yuan, Jin Yang, Yong Wang, Zu-Hai Ma, Yu Chen, and Xin-Xing Zhou. "Giant and controllable in-plane spin angular shifts in bulk and ultrathin magnetic materials." Acta Physica Sinica 72, no. 1 (2022): 014201. http://dx.doi.org/10.7498/aps.72.20221643.

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The magneto-optical Kerr effect (MOKE) refers to the rotation of the polarization plane when a linearly polarized light is reflected at the surface of magnetic material. The MOKE reveals the magnetization of the optical properties of magnetic material and can be characterized by the dielectric tensor containing the magneto-optical constant. Thus, exploring the MOKE requires very precise determination of the magneto-optical constant. The photonic spin Hall effect (PSHE), which corresponds to the lateral and in-plane spin-dependent splitting of the beam, can be used as an effective method to characterize the magneto-optical constant due to its advantage of being extremely sensitive to changes in the physical parameters of the material. Most of the previous studies only considered the case of a single thickness of magnetic material and a single MOKE and need to introduce complex weak measurement techniques to observe the photonic spin Hall effect. In this work, we theoretically investigate the in-plane spin angular shifts in three MOKE cases in bulk and ultrathin magnetic materials. We can effectively tune the in-plane angular displacements of different magnetic material thickness by changing the magnetic field direction corresponding to different MOKEs and changing the magneto-optical constants (including amplitude and phase). The research results show that in the case of bulk and ultrathin magnetic materials, the internal spin angular displacements under different MOKEs will show different trends when the magneto-optical constants change the amplitude and phase, especially in ultra-thin magnetic material. In the lateral Kerr effect in thin material, the photon in-plane angular displacement does not affect the change of the magneto-optical constant, but in other cases, the amplitude relative to the phase has a much larger effect on the photon in-plane angular displacement. In this regard, we propose a new method which can directly determine the amplitude and phase of the magneto-optical constant by using the huge in-plane spin angular displacement without considering the weak measurements and can also judge different MOKEs according to the variation of the in-plane angular displacement in the bulk and ultrathin magnetic materials. This method not only provides a new probe for measuring magneto-optical constants but also expands the study of spin photonics.

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Choi, Gyung-Min. "Magneto-Optical Kerr Effect Driven by Spin Accumulation on Cu, Au, and Pt." Applied Sciences 8, no. 8 (August 15, 2018): 1378. http://dx.doi.org/10.3390/app8081378.

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The magneto-optical Kerr effect (MOKE) has recently been achieved on non-ferromagnetic metals by injecting spin currents. To use the magneto-optical Kerr effect as a quantitative tool, it is crucial to study the relationship between the Kerr rotation angle and the spin accumulation on non-ferromagnets. In this work, I measure a transient magneto-optical Kerr rotation on non-ferromagnetic metals of Cu, Au, and Pt driven by an ultrafast spin current from an adjacent ferromagnetic metal. Through comparing the measured Kerr rotation and the calculated spin accumulation, I determine the conversion ratio between the Kerr rotation and the spin accumulation to be: −4 × 10−9 (real part), −2.5 × 10−8 (real part), and −3 × 10−9 (imaginary part) rad m A−1 for Cu, Au, and Pt, respectively, at a wavelength of 784 nm.

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Liu, H., Agne Ciuciulkaite, Vassilios Kapaklis, D. Karaiskaj, and D. A. Arena. "Enhanced optical mode coherence in exchange coupled soft magnetic multilayers." Journal of Applied Physics 131, no. 21 (June 7, 2022): 213902. http://dx.doi.org/10.1063/5.0093827.

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We report on an all-optical investigation of coupled spin excitation modes in a series of magnetic trilayer structures. Using time-resolved magneto-optic Kerr effect (tr-MOKE) magnetometry, we observe multi-mode coherent spin excitations in [Formula: see text]/Ru/[Formula: see text] multilayers even though the tr-MOKE optical detection is sensitive only to the [Formula: see text] magnetization dynamics. Frequency shifts of the different modes indicate that the coupling between the [Formula: see text] and [Formula: see text] layers varies from anti-ferromagnetic to ferromagnetic to uncoupled as the Ru spacer layer thickness is increased from 8 Å to 200 Å. The lifetime of the high frequency coherent oscillations in the [Formula: see text] layer increases by over 200%–300% even in the case of uncoupled [Formula: see text] and [Formula: see text] layers with a 200 Å thick Ru spacer. The results suggest an additional method to decrease the damping of high-moment alloys in layered magnetic nanostructures.

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Zhang, Weiwei, Zhanghua Chen, Vladimir I. Belotelov, and Yujun Song. "Longitudinal Magneto-Optical Kerr Effect of Nanoporous CoFeB and W/CoFeB/W Thin Films." Coatings 12, no. 2 (January 20, 2022): 115. http://dx.doi.org/10.3390/coatings12020115.

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Nanoporous Co40Fe40B20 (CoFeB) and sandwich tungsten (W)/CoFeB/W thin films were fabricated via an anodic aluminum oxide (AAO) template-assisted magneto sputtering process. Their thickness-dependent magneto-optical Kerr effect (MOKE) hysteresis loops were investigated for enhanced Kerr rotation. Control of the Kerr null points of the polarized reflected light can be realized via the thicknesses of the CoFeB layers and W layers. Simulation of the thickness-dependent phase difference change by the finite element method reveals the existence of the two Kerr null points for W/CoFeB/W thin films, matching the experimental result very well. However, there are two additional Kerr null points for pure CoFeB thin films according to the simulation by comparing with the experimental result (only one). Theoretical analysis indicates that the different Kerr null points between the experimental result and the simulation are mainly due to the enhanced inner magnetization in the ferromagnetic CoFeB layer with the increased thickness, which is usually omitted in the simulation. Clearly, the introduction of non-ferromagnetic W layers can experimentally regulate the Kerr null points of ferromagnetic thin films. Moreover, construction of W/CoFeB/W sandwich thin films can greatly increase the highest magneto-optical susceptibility and the saturated Kerr rotation angle when compared with CoFeB thin films of the same thickness.

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Prakash, Chandra, Rajagopal Srivatsan, Himanshu Fulara, and Sujeet Chaudhary. "Tailoring the Hysteresis Loop of the Si/Cu(10nm)/FeMn(10-30nm)/CoFeB(10nm) Bilayer System." Advanced Materials Research 622-623 (December 2012): 695–99. http://dx.doi.org/10.4028/www.scientific.net/amr.622-623.695.

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The dependence of hysteretic properties of FeMn/CoFeB (AF/FM) thin bilayers on AF thickness and magnetic annealing temperature is systematically investigated for possible applications in spin-valve devices. Inducement of an easy axis after magnetic annealing is established. The anisotropy is studied by investigating the coercivity along and perpendicular to the induced easy axis using Magneto-Optic Kerr Effect (MOKE) and the AF texture is ascertained by XRD. The existence of an optimum annealing temperature, for which the maximum change in coercivity occurs for a particular AF thickness, is evidenced. The maxima in HC of the bilayer with thickness of AF layer were correlated with FCC FeMn (111) texture of the sample.

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Paliwal, Ayushi, Savita Sharma, Monika Tomar, and Vinay Gupta. "Impact of plasma dynamics on magneto optic kerr effect (MOKE) in Mn doped BFO thin films." Physica B: Condensed Matter 571 (October 2019): 57–63. http://dx.doi.org/10.1016/j.physb.2019.06.054.

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Fan, W. J., Z. Shi, F. L. Chen, and S. M. Zhou. "Tuning Effects of Spin–Orbit Coupling in L10 Ordered and Disordered FePdPt Films." SPIN 05, no. 03 (September 2015): 1530004. http://dx.doi.org/10.1142/s2010324715300042.

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Effects of spin–orbit coupling (SOC) on magnetocrystalline anisotropy, magneto-optical Kerr effect (MOKE), magnetic damping parameter and anomalous Hall effect (AHE) have been studied in theory extensively. In contrast, few experimental reports have appeared on these issues. In this review paper, we introduce our recent experimental investigation on the SOC tuning effects on the perpendicular magnetic anisotropy, polar MOKE, intrinsic magnetic damping parameter and AHE in L10 ordered [Formula: see text] ternary alloys. We also outline the SOC effects in polycrystalline disordered [Formula: see text] films for comparison.

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Kerkache, L., A. Layadi, M. Hemmous, A. Guittoum, M. Mebarki, N. Tiercelin, A. Klimov, V. Preobrazhensky, and P. Pernod. "MOKE Magnetometer Studies of Evaporated Ni and Ni/Cu Thin Films onto Different Substrates." SPIN 09, no. 01 (March 2019): 1950006. http://dx.doi.org/10.1142/s2010324719500061.

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The Magneto-Optic Kerr Effect (MOKE) technique has been used to investigate the magnetic properties of Ni thin films, with thickness [Formula: see text] ranging from 9 to 163[Formula: see text]nm, evaporated onto several substrates (glass, Si (111), mica and Cu) with and without an evaporated Cu underlayer. The MOKE observations were correlated with the surface morphology inferred from Scanning Electron Microscope images and with the structural properties (grain size and strain). Some interesting behaviors of the coercive field (with values in the 2 to 151 Oe range), the squareness (between 0.1 and 0.91) and the saturation field (25–320 Oe) are observed as a function of [Formula: see text], the substrate and the Cu underlayer. A thickness-dependent stress-induced anisotropy is found in these films. The differences between the present MOKE results and the ones obtained from the Vibrating Sample magnetometer (VSM) are highlighted. The former describe the surface magnetism of these systems, while the latter are attributed to the whole volume of the sample.

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Bezdidko, Oleksandr, Shkurdoda Yuriy, Olena Fedchenko, Iryna Cheshko, and Serhiy Protsenko. "Magneto-optical properties of two-layer film systems based on Fe and Cr." International Journal of Modern Physics B 34, no. 27 (October 14, 2020): 2050251. http://dx.doi.org/10.1142/s0217979220502513.

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The results of the investigation of two-layer Fe/Cr systems using the magneto-optical Kerr effect (MOKE) are presented in this paper. The samples were obtained by thermal evaporation in a vacuum with a thickness of individual layers from 2 nm to 50 nm. It was found that the presence of the Cr layer significantly affects the values of the coercivity and the Kerr angle. At a substrate temperature of 450 K, the value of the coercivity is almost half that of the same sample obtained at room temperature of the substrate. In addition, the influence of the order of deposition of layers, as well as the effect of a thin gold protective layer on the parameters measured by the Kerr method, is shown. These studies have shown that the MOKE can be used as an additional method for studying the composition of multilayer systems, granular alloys and spin-valve systems, using specific software methods.

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Wang, Ke, Yang Xiang, Chuanwen Chen, Fengjiang Zhuang, Xuefeng Wu, and Roger Ward. "Direct observation of magnetic exchange-spring development in epitaxial DyFe2/YFe2 superlattices by magneto-optical Kerr effect." Functional Materials Letters 08, no. 05 (September 29, 2015): 1550053. http://dx.doi.org/10.1142/s1793604715500538.

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The magnetic reversal properties of molecular beam epitaxy (MBE) grown Laves phase single crystal YFe 2-dominated DYFe 2/ YFe 2 superlattices were investigated using magneto-optical Kerr effect (MOKE) measurements. Single crystal DYFe 2/ YFe 2 superlattices with a thickness ratio of 1:4 were MBE-grown with a (110) growth direction. In the epitaxial superlattices, the development of exchange-spring structure during magnetic reversal is revealed by both magneto-optical reflectivity and Kerr rotation angle loops. The bending fields of the samples are found to be close due to nonideal anisotropy in both hard and soft layers. For the sample with thin soft/hard layers, large magneto-optical reflectivity change up to 0.25% was observed. This can be related with rotation of Fe spins in YFe 2 soft layers under a low pinning field, in consistence with the small switching field of thin DYFe 2 hard layers measured experimentally.

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Uebo, Koki, Yuto Shiokawa, Ryunosuke Takahashi, Suguru Nakata, and Hiroki Wadati. "Development of a magneto-optical Kerr microscope using a 3D printer." F1000Research 12 (July 20, 2023): 860. http://dx.doi.org/10.12688/f1000research.133292.1.

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Background: Magneto-optical Kerr effect (MOKE) microscopes are powerful experimental tools to observe magnetic domains in magnetic materials. These devices are, however, typically large, unportable, and expensive (∼ several million yen), and therefore prevent many researchers in the field of materials science from easy access to study real-space images of magnetic domains. Methods: To overcome these issues, we utilize data from ”The OpenFlexure Project” developed by the University of Bath and the University of Cambridge. The purpose of this project is to make high-precision mechanical positioning of the studied sample available to anyone with a 3D printer, especially for use in microscopes. We built a low-cost and portable MOKE microscope device by a 3D printer. We redesigned the 3D modeling data of an ordinary optical microscope provided by The OpenFlexure project and incorporated additional elements such as optical polarizers and an electro-magnetic coil into the primarily designed microscope that did not originally have these elements. Results: We successfully observed magnetic domains and their real-space motions induced by magnetic fields using the palm-sized low-cost MOKE microscope, which costs approximately 20,000 yen in raw materials to construct. Conclusions: Our methodology to assemble a low-cost MOKE microscope will enable researchers working in the field of materials science to more easily observe magnetic domains without commercial equipment.

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Uchimura, Tomohiro, Ju-Young Yoon, Yuma Sato, Yutaro Takeuchi, Shun Kanai, Ryota Takechi, Keisuke Kishi, et al. "Observation of domain structure in non-collinear antiferromagnetic Mn₃Sn thin films by magneto-optical Kerr effect." Applied Physics Letters 120, no. 17 (April 25, 2022): 172405. http://dx.doi.org/10.1063/5.0089355.

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We perform hysteresis-loop measurement and domain imaging for [Formula: see text]-oriented D019-Mn3+ xSn1- x ([Formula: see text]) thin films using the magneto-optical Kerr effect (MOKE) and compare it with the anomalous Hall effect (AHE) measurement. We obtain a large Kerr rotation angle of 10 mdeg, comparable with bulk single-crystal Mn3Sn. The composition x dependence of AHE and MOKE shows a similar trend, suggesting the same origin, i.e., the non-vanishing Berry curvature in the momentum space. Magnetic domain observation at the saturated state shows that x dependence of AHE and MOKE is explained by the amount of the reversible area that crucially depends on the crystalline structure of the film. Furthermore, in-depth observation of the reversal process reveals that the reversal starts with nucleation of sub-micrometer-scale domains dispersed in the film, followed by domain expansion, where the domain wall preferentially propagates along the [Formula: see text] direction. Our study provides a basic understanding of the spatial evolution of the reversal of the chiral-spin structure in non-collinear antiferromagnetic thin films.

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Genuzio, Francesca, Tomasz Giela, Matteo Lucian, Tevfik Onur Menteş, Carlo Alberto Brondin, Giuseppe Cautero, Piotr Mazalski, Stefano Bonetti, Jozef Korecki, and Andrea Locatelli. "A UHV MOKE magnetometer complementing XMCD-PEEM at the Elettra Synchrotron." Journal of Synchrotron Radiation 28, no. 3 (March 30, 2021): 995–1005. http://dx.doi.org/10.1107/s1600577521002885.

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We report on a custom-built UHV-compatible Magneto-Optical Kerr Effect (MOKE) magnetometer for applications in surface and materials sciences, operating in tandem with the PhotoEmission Electron Microscope (PEEM) endstation at the Nanospectroscopy beamline of the Elettra synchrotron. The magnetometer features a liquid-nitrogen-cooled electromagnet that is fully compatible with UHV operation and produces magnetic fields up to about 140 mT at the sample. Longitudinal and polar MOKE measurement geometries are realized. The magneto-optical detection is based on polarization analysis using a photoelastic modulator. The sample manipulation system is fully compatible with that of the PEEM, making it possible to exchange samples with the beamline endstation, where complementary X-ray imaging and spectroscopy techniques are available. The magnetometer performance is illustrated by experiments on cobalt ultra-thin films, demonstrating close to monolayer sensitivity. The advantages of combining in situ growth, X-ray Magnetic Circular Dichroism imaging (XMCD-PEEM) and MOKE magnetometry into a versatile multitechnique facility are highlighted.

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MOHANTA, MAHESWARI, S. K. PARIDA, ANANYA SAHOO, and V. R. R. MEDICHERLA. "GROWTH AND MAGNETIC PROPERTIES OF DC MAGNETRON SPUTTERED Co0.2Fe0.8 THIN FILM." Surface Review and Letters 28, no. 06 (April 7, 2021): 2150053. http://dx.doi.org/10.1142/s0218625x21500530.

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We report the growth and characterization of the [Formula: see text][Formula: see text] thin film. The thin film was deposited on Si (100) substrate by using a direct-current magnetron sputtering deposition technique. The Grazing Incidence X-ray Diffraction (GIXRD) analysis suggests a bcc crystal structure with a lattice constant of 2.87[Formula: see text]. The X-ray reflectivity (XRR) data analysis shows the thickness of the [Formula: see text][Formula: see text] thin film is about 30 nm. The Energy Dispersive X-ray (EDAX) analysis shows the presence of 22.94% of Co and 77.06% of Fe in [Formula: see text][Formula: see text] thin film. The Magneto-Optic Kerr Effect (MOKE) technique was used to investigate the magnetic properties and results support that [Formula: see text][Formula: see text]thin film exhibits soft magnetic character. The analysis of the M–H loop suggests that the value of the coercive field decreases with the increase of angle with respect to the magnetic easy axis. The MOKE measurement suggests that [Formula: see text][Formula: see text] thin film alloy exhibits the least anisotropy with two-fold magnetic anisotropy. Magnetization reversibility was observed by using high-resolution Kerr microscopy. The domain images showed that reversibility occurs through nucleation and domain wall motion. Magnetic anisotropy dispersion was also observed which may be due to the misalignment of grains in the film due to which we got the least anisotropy. These properties of the prepared sample found potential application in the field of spintronics and magnetic sensors.

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Sanz-Hernández, Dédalo, Luka Skoric, Miguel Ángel Cascales-Sandoval, and Amalio Fernández-Pacheco. "Probing 3D magnetic nanostructures by dark-field magneto-optical Kerr effect." Journal of Applied Physics 133, no. 4 (January 28, 2023): 043901. http://dx.doi.org/10.1063/5.0132250.

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Magneto-optical techniques are key tools for the characterization of magnetic effects at a nanoscale. Here, we present the dark-field magneto-optical Kerr effect (DFMOKE), a technique we have recently developed for the characterization of three-dimensional magnetic nanostructures. We introduce the principles of DFMOKE, based on the separation of an incident beam into multiple reflected beams when focusing on a 3D nano-geometry. We show the key modifications needed in a standard focused MOKE magnetometer to perform these measurements. Finally, we showcase the power of this method by detecting the magnetic switching of a single tilted 3D nanowire, independently from the switching of a magnetic thin film that surrounds it. We obtain independent and simultaneous switching detection of the nanowire and the film for all nanowire dimensions investigated, allowing us to estimate a magnetic sensitivity of 7 × 10−15 A m2 for DFMOKE in the setup used. We conclude the article by providing perspectives of future avenues where DFMOKE can be a very powerful characterization tool in the future investigations of 3D magnetic nanostructures.

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Zhang, Weiwei, Haizi Yao, and Yao Lu. "Surface plasmon resonance enhanced transverse magneto-optical Kerr effect and the detection performance of nanopore arrays." Journal of Optics 24, no. 3 (February 14, 2022): 035003. http://dx.doi.org/10.1088/2040-8986/ac4436.

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Abstract The introduction of a magnetic component to the surface plasmon resonance (SPR) structure to form a magneto-optical surface plasmonic resonance (MOSPR) detector is an effective method for enhancing the detection limit for small molecules at low concentrations. This is important for biosensing, early disease diagnosis, drug discovery, and the detection of contamination in solutions and gases. In this study, an MOSPR crystal composed of a Co6Ag94 slab covered by a subwavelength periodic square array of gold (Au) nanopores was designed to theoretically examine the mechanism by which MOSPR crystals detect glucose concentrations through the transverse magneto-optical Kerr effect (T-MOKE). Owing to the excitation of SPR at the interface between the glucose solution and Au film, a Fano-like sharp T-MOKE spectrum with a narrow linewidth and a high amplitude was obtained, thus producing a high sensitivity of 159° RIU−1 and a high figure of merit of the order of 103 RIU−1. This corresponds to a glucose detection limit of 0.0066 g ml−1, which is more accurate than that previously reported. This design provides an alternative method for detecting analytes’ concentrations in aqueous environments.

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Cheskis, Dima. "Magneto-Optical Tools to Study Effects in Dirac and Weyl Semimetals." Symmetry 12, no. 9 (August 25, 2020): 1412. http://dx.doi.org/10.3390/sym12091412.

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Research regarding topological Dirac and Weyl semimetals contributes to our understanding not only of the field of solid-state physics, but also the field of high-energy physics as the physics of Dirac and Weyl semimetals resembles the physics of Dirac and Weyl massless fermions. In condensed matter physics, the Weyl nodes are detached in momentum space and may be realized as emergent quasiparticles with a distinct chirality, left-handed or right-handed. These states lead to phenomena like the chiral anomaly and the anomalous Hall effect (AHE). Furthermore, the combination of quantum effects and magnetic effects in magnetic Weyl semimetals is very intriguing. Magneto-optical tools, which are usually used to study magnetic phenomena, also contribute to magnetic Weyl semimetals. Moreover, with the magneto-optical technique, it is possible to follow the dynamics of the processes and to study the lifetime of the Weyl states. In this work, we review and discuss the effects of using magneto-optical tools for studying quantum effects like the chiral anomaly or magnetic effects in magnetic Weyl and Dirac systems using the magneto-optical Kerr effect (MOKE) or Faraday systems including a single detection and imaging. Examples of using magneto-optical systems in the research of ultrafast magnetic dynamics of thin polycrystalline nickel and permaloy are reviewed as are the magnetic spatial dynamics by employing magneto-optical Kerr or Faraday microscopy tools with ferromagnetic thin films. Interestingly, the excitation of a circularly polarized femtosecond laser pulse could lead to the breakage of time-reversal symmetry and to the transformation of the Dirac state to the Floquet–Weyl semimetal state. The development of a suitable ultrafast magneto-optical system for Weyl systems is discussed, and the practical difficulties for the realization of such a system are considered.

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SENZ, V., A. KLEIBERT, and J. BANSMANN. "TRANSVERSE MAGNETO-OPTICAL KERR EFFECT IN THE SOFT X-RAY REGIME OF ULTRATHIN IRON FILMS AND ISLANDS ON W(110)." Surface Review and Letters 09, no. 02 (April 2002): 913–19. http://dx.doi.org/10.1142/s0218625x02003159.

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The transverse magneto-optical Kerr effect (T-MOKE) in the soft X-ray regime is used to investigate the magnetic properties of ultrathin epitaxial Fe(110) films and thermally created epitaxial Fe islands on W(110). The measurements have been carried out at the Fe 2p core levels with tunable, linearly polarized synchrotron radiation. Besides the chemical selectivity T-MOKE at core levels is characterized by a much larger sensitivity compared to the visible regime. We have analyzed the transition from thin films to a three-dimensional island system at a thickness of 4 ML and the magnetic behavior when increasing the iron coverage to 8 ML. The Fe island system is characterized by a rotation of the easy magnetization axis in this coverage regime.

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Kumar, Anil, Ranjeet Brajpuriya, and Priti Singh. "Thickness-Dependent Structural and Magnetic Study of Co/Si/Co Trilayers Grown by Ion Beam Sputtering." SPIN 08, no. 02 (June 2018): 1850005. http://dx.doi.org/10.1142/s2010324718500054.

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The magnetic properties of the metal/semiconductor structure can be modulated by the semiconductor layer thickness and therefore in the present paper, a series of trilayers of ion beam sputtered Cobalt–Silicon–Cobalt (Co/Si/Co) were grown to study the interface characteristics and their connections with magnetic properties. The thickness of Co layer, [Formula: see text], is fixed to 3[Formula: see text]nm, while varying the thickness of Si sandwich layer, [Formula: see text], from 1.5[Formula: see text]nm to 4[Formula: see text]nm, respectively. Grazing incidence X-ray diffraction (GIXRD), grazing incidence X-ray reflectivity (GIXRR), Atomic Force Microscopy (AFM) and Magneto-Optic Kerr Effect (MOKE) techniques were employed to study the crystal structure, surface and interface structure, morphology and magnetic characteristics of thin films. X-ray reflectivity measurements show substantial intermixing between the layers leading to trilayers of complicated structure at the interface during deposition. At [Formula: see text][Formula: see text]nm, whole Si layer is converted into silicide, whereas at higher spacer layer thickness ([Formula: see text]), in addition to silicide layer, an unreacted elemental layer of Si also remains in the spacer. A magneto-optical measurement reveals the presence of anti-ferromagnetic coupling in these samples and the strength of coupling between Co layers is found to be depended on [Formula: see text].

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Quach, Duy-Truong. "MAGNETIC PROPERTIES AND DOMAIN STRUCTURE OF CoFeB/Pd MULTILAYERS WITH PERPENDICULAR MAGNETIC ANISOTROPY." Vietnam Journal of Science and Technology 57, no. 6 (November 20, 2019): 685. http://dx.doi.org/10.15625/2525-2518/57/6/13885.

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The magnetic properties and domain structure of (CoFeB/Pd)n (n = 2 – 10) multilayers with perpendicular magnetic anisotropy have been investigated systematically. The study has been carried out by using vibration sample magnetometer (VSM) and magneto-optical Kerr effect (MOKE) microscope. The results show clear changes of magnetic hysteresis and domain structure when increasing the number of bilayer (n) from 2 to 10. With increasing the number of bilayer, the multilayers’ hysteresis loops change from square-shaped to slanted, while domain structures change from circular-like to maze.

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Boukelkoul, M., M. Kharoubi, and A. Haroun. "Magnetic and magneto-optical properties of ultrathin films of iron epitaxied on iridium (001)." Canadian Journal of Physics 86, no. 12 (December 1, 2008): 1421–26. http://dx.doi.org/10.1139/p08-103.

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We have theoretically studied the structural, magnetic, and magneto-optical behaviours of Fe ultra-thin films pseudomorphically epitaxied on semi-infinite Ir(001). The magnetic film crystallizes in the body-centered tetragonal (bct) structure with a tetragonality ratio 1.21. The new crystalline structure of iron in the magnetic film enhances the magnetic properties and a correlation between the interlayer spacing and the magnetic moment is found. The calculation of the magnetic properties shows a ferromagnetic interlayer coupling. The polar magneto-optical Kerr effect (P-MOKE) spectra are calculated over a photon energy range extended to 10~eV. The microscopic origin of the most interesting features is explained from interband transitions in various regions of the Brillouin zone.PACS Nos.: 78.20.Bh, 78.20.Ls

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Schümmer, Andreas, H. Ch Mertins, Claus Michael Schneider, Roman Adam, Stefan Trellenkamp, Rene Borowski, Daniel Emil Bürgler, Larissa Juschkin, and Ulf Berges. "A scanning reflection X-ray microscope for magnetic imaging in the EUV range." Journal of Synchrotron Radiation 26, no. 6 (November 1, 2019): 2040–49. http://dx.doi.org/10.1107/s1600577519012219.

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The mechanical setup of a novel scanning reflection X-ray microscope is presented. It is based on zone plate optics optimized for reflection mode in the EUV spectral range. The microscope can operate at synchrotron radiation beamlines as well as at laboratory-based plasma light sources. In contrast to established X-ray transmission microscopes that use thin foil samples, the new microscope design presented here allows the investigation of any type of bulk materials. Importantly, this permits the investigation of magnetic materials by employing experimental techniques based on X-ray magnetic circular dichroism, X-ray linear magnetic dichroism or the transversal magneto-optical Kerr effect (T-MOKE). The reliable functionality of the new microscope design has been demonstrated by T-MOKE microscopy spectra of Fe/Cr-wedge/Fe trilayer samples. The spectra were recorded at various photon energies across the Fe 3p edge revealing the orientation of magnetic domains in the sample.

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Varlamov, Pavel, Anna Semisalova, Anh Dung Nguyen, Michael Farle, Yannis Laplace, Michele Raynaud, Olivier Noel, Paolo Vavassori, and Vasily Temnov. "Femtosecond Laser Ablation-Induced Magnetic Phase Transformations in FeRh Thin Films." Magnetochemistry 9, no. 7 (July 18, 2023): 186. http://dx.doi.org/10.3390/magnetochemistry9070186.

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In this study, we present a novel investigation into the magnetic and morphological properties of equiatomic B2-ordered FeRh thin films irradiated with single high-intensity ultrashort laser pulses. The goal is to elucidate the effect of femtosecond laser ablation on the magnetic properties of FeRh. We employed Scanning Magneto-Optical Kerr Effect (S-MOKE) microscopy to examine the magnetic phase after laser processing, providing high spatial resolution and sensitivity. Our results for the first time demonstrated the appearance of a magneto-optical signal from the bottom of ablation craters, suggesting a transition from antiferromagnetic to ferromagnetic behavior. Fluence-resolved measurements clearly demonstrate that the ablation threshold coincides with the threshold of the antiferromagnet-to-ferromagnet phase transition. The existence of such a magnetic phase transition was independently confirmed by temperature-dependent S-MOKE measurements using a CW laser as a localized heat source. Whereas the initial FeRh film displayed a reversible antiferromagnet-ferromagnet phase transition, the laser-ablated structures exhibited irreversible changes in their magnetic properties. This comprehensive analysis revealed the strong correlation between the femtosecond laser ablation process and the magnetic phase transformation in FeRh thin films.

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Tao, Zhensheng, Wenjing You, Phoebe Tengdin, Cong Chen, Xun Shi, Dmitriy Zusin, Yingchao Zhang, et al. "The nature of the ultrafast magnetic phase transition in nickel revealed by correlating EUV-MOKE and ARPES spectroscopies." EPJ Web of Conferences 205 (2019): 04002. http://dx.doi.org/10.1051/epjconf/201920504002.

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By correlating time- and angle-resolved photoemission (Tr-ARPES) and time-resolved transverse- magneto-optical Kerr effect (Tr-TMOKE) measurements, both at extreme ultraviolet (EUV) wavelengths, we uncover the nature of the ultrafast photoinduced magnetic phase transition in Ni. This allows us to explain the ultrafast magnetic response of Ni at all laser fluences - from a small reduction of the magnetization at low laser fluences, to complete quenching at high laser fluences. We provide an alternative explanation to the fluence-dependent recovery timescales commonly observed in ultrafast magneto-optical spectroscopies on ferromagnets: it is due to the bulk-averaging effect and different depths of sample exhibit distinct dynamics, depending on whether a magnetic phase transition is induced. We also show evidence of two competing channels with two distinct timescales in the recovery process, that suggest the presence of coexisting phases in the material.

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Yu, Ying, Shu Hong Xie, and Qing Feng Zhan. "Effect of Thickness on Mechanically Tunable Magnetic Anisotropy of FeGa Thin Films Deposited on Flexible Substrates." Materials Science Forum 815 (March 2015): 227–32. http://dx.doi.org/10.4028/www.scientific.net/msf.815.227.

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A practical way to manipulate the magnetic anisotropy of magnetostrictive FeGa thin films grown on flexible polyethylene terephthalate (PET) substrates is introduced in this study. The effect of film thickness on magnetic properties and magnetostriction constant of polycrystalline FeGa thin films was investigated. The anisotropy field Hk of flexible FeGa films, i.e., the saturation field determined by fitting the hysteresis curves measured along the hard axis, was enhanced with increasing the tensile strain applied along the easy axis of the thin films, but this enhancement via strain became unconspicuous with increasing the thickness of FeGa films. In order to study the magnetic sensitivity of thin films responding to the external stress, we applied different strains on these films and measure the corresponding anisotropy field. Moreover, the effective magnetostriction constant of FeGa films was calculated from the changes of both anisotropy field and external strain based on the Villari effect. A Neel’s phenomenological model was developed to illustrate that the effective anisotropy field of FeGa thin films was contributed from both the constant volume term and the inverse thickness dependent surface term. Therefore, the magnetic properties for the volume and surface of FeGa thin films were different, which has been verified in this work by using vibrating sample magnetometer (VSM) and magneto-optic Kerr effect (MOKE) system. The anisotropy field contributed by the surface of FeGa film and obtained by MOKE is smaller than that contributed by the film volume and measured by VSM. We ascribed the difference in Hk to the relaxation of the effective strain applied on the films with increasing the thickness of films.

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Martín Valderrama, Carmen, Mikel Quintana, Ane Martínez-de-Guerenu, Tomoki Yamauchi, Yuki Hamada, Yuichiro Kurokawa, Hiromi Yuasa, and Andreas Berger. "Insertion layer magnetism detection and analysis using transverse magneto-optical Kerr effect (T-MOKE) ellipsometry." Journal of Physics D: Applied Physics 54, no. 43 (August 10, 2021): 435002. http://dx.doi.org/10.1088/1361-6463/ac0d2a.

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Benyahia, K., Z. Nabi, Rajeev Ahuja, and A. Khalfi. "Magneto-optical Kerr effect (MOKE) of the rare-earth silicide ErSi2 using ab-initio calculations." Current Applied Physics 9, no. 5 (September 2009): 925–27. http://dx.doi.org/10.1016/j.cap.2008.09.009.

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Wedding, J. B., M. Li, and G. C. Wang. "Magnetization reversal of a thin polycrystalline cobalt film measured by the magneto-optic Kerr effect (MOKE) technique and field-dependent magnetic force microscopy." Journal of Magnetism and Magnetic Materials 204, no. 1-2 (September 1999): 79–89. http://dx.doi.org/10.1016/s0304-8853(99)00433-3.

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35

Jana, S., R. Knut, S. Muralidhar, R. S. Malik, R. Stefanuik, J. Åkerman, O. Karis, C. Schüßler-Langeheine, and N. Pontius. "Experimental confirmation of the delayed Ni demagnetization in FeNi alloy." Applied Physics Letters 120, no. 10 (March 7, 2022): 102404. http://dx.doi.org/10.1063/5.0080331.

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Element-selective techniques are central for the understanding of ultrafast spin dynamics in multi-element materials, such as magnetic alloys. Recently, however, it turned out that the commonly used technique of the transverse magneto-optical Kerr effect (T-MOKE) in the extreme ultraviolet range may have issues with unwanted crosstalk between different elemental signals and energy-dependent non-linear response. This problem can be sizeable, which puts recent observations of ultrafast spin transfer from Fe to Ni sites in FeNi alloys into question. In this study, we investigate the Fe-to-Ni spin transfer in a crosstalk-free time-resolved x-ray magnetic circular dichroism (XMCD) experiment with a reliable time reference. With XMCD near the absorption maxima, we find a very similar Fe and Ni dynamics as with T-MOKE from identical samples. Considering the potential non-linearities of the T-MOKE response, such a good agreement in our findings is remarkable. Our data provide the ongoing discussion about ultrafast spin-transfer mechanisms in FeNi systems with a broader experimental basis.

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Khosravi, Payam, Seyyed Ali Seyyed Seyyed Ebrahimi, Zahra Lalegani, and Bejan Hamawandi. "Anisotropic Magnetoresistance Evaluation of Electrodeposited Ni80Fe20 Thin Film on Silicon." Micromachines 13, no. 11 (October 22, 2022): 1804. http://dx.doi.org/10.3390/mi13111804.

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In this study, a simple growth of permalloy NiFe (Py) thin films on a semiconductive Si substrate using the electrochemical deposition method is presented. The electrodeposition was performed by applying a direct current of 2 mA/cm2 during different times of 120 and 150 s and thin films with different thicknesses of 56 and 70 nm were obtained, respectively. The effect of Py thickness on the magnetic properties of thin films was investigated. Field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDS), atomic force microscopy (AFM), ferromagnetic resonance (FMR), anisotropic magnetoresistance (AMR), and magneto-optic Kerr effect (MOKE) analyses were performed to characterize the Py thin films. It was observed that the coercivity of the Py thin film increases by increasing the thickness of the layer. Microscopic images of the layers indicated granular growth of the Py thin films with different roughness values leading to different magnetic properties. The magnetic resonance of the Py thin films was measured to fully describe the magnetic properties of the layers. The magnetoresistance ratios of deposited Py thin films at times of 120 and 150 s were obtained as 0.226% and 0.235%, respectively. Additionally, the damping constant for the deposited sample for 120 s was estimated as 1.36 × 10−2, which is comparable to expensive sputtered layers’ characteristics.

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Stebliy, Maxim E., Alexander G. Kolesnikov, Alexey V. Ognev, Alexander S. Samardak, and Ludmila A. Chebotkevich. "Manipulation of magnetic vortex parameters in disk-on-disk nanostructures with various geometry." Beilstein Journal of Nanotechnology 6 (March 10, 2015): 697–703. http://dx.doi.org/10.3762/bjnano.6.70.

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Magnetic nanostructures in the form of a sandwich consisting of two permalloy (Py) disks with diameters of 600 and 200 nm separated by a nonmagnetic interlayer are studied. Magnetization reversal of the disk-on-disk nanostructures depends on the distance between centers of the small and big disks and on orientation of an external magnetic field applied during measurements. It is found that manipulation of the magnetic vortex chirality and the trajectory of the vortex core in the big disk is only possible in asymmetric nanostructures. Experimentally studied peculiarities of a motion path of the vortex core and vortex parameters by the magneto-optical Kerr effect (MOKE) magnetometer are supported by the magnetic force microscopy imaging and micromagnetic simulations.

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Corte-Leon, Paula, Valentina Zhukova, Alexandr Chizhik, Juan Maria Blanco, Mihail Ipatov, Lorena Gonzalez-Legarreta, and Arcady Zhukov. "Magnetic Microwires with Unique Combination of Magnetic Properties Suitable for Various Magnetic Sensor Applications." Sensors 20, no. 24 (December 16, 2020): 7203. http://dx.doi.org/10.3390/s20247203.

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There is a pressing demand to improve the performance of cost-effective soft magnetic materials for use in high performance sensors and devices. Giant Magneto-impedance effect (GMI), or fast single domain wall (DW) propagation can be observed in properly processed magnetic microwires. In this paper we have identified the routes to obtain microwires with unique combination of magnetic properties allowing observation of fast and single DW propagation and GMI effect in the same microwire. By modifying the annealing conditions, we have found the appropriate regimes allowing achievement of the highest GMI ratio and the fastest DW dynamics. The observed experimental results are discussed considering the radial distribution of magnetic anisotropy and the correlation of GMI effect, and DW dynamics with bulk and surface magnetization processes. Studies of both Fe- and Co-rich microwires, using the magneto-optical Kerr effect, MOKE, provide information on the magnetic structure in the outer shell of microwires. We have demonstrated the existence of the spiral helical structure in both studied microwires. At the same time, torsion mechanical stresses induce helical bistability in the same microwires, which allow us to consider these microwires as materials suitable for sensors based on the large Barkhausen jump.

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Kumar, D., P. Gupta, and A. Gupta. "In situ surface magneto-optical Kerr effect (s-MOKE) study of ultrathin soft magnetic FeCuNbSiB alloy films." Materials Research Express 1, no. 4 (October 20, 2014): 046405. http://dx.doi.org/10.1088/2053-1591/1/4/046405.

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Demirer, Figen Ece, Chris van den Bomen, Reinoud Lavrijsen, Jos J. G. M. van der Tol, and Bert Koopmans. "Design and Modelling of a Novel Integrated Photonic Device for Nano-Scale Magnetic Memory Reading." Applied Sciences 10, no. 22 (November 21, 2020): 8267. http://dx.doi.org/10.3390/app10228267.

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Design and simulations of an integrated photonic device that can optically detect the magnetization direction of its ultra-thin (∼12 nm) metal cladding, thus ‘reading’ the stored magnetic memory, are presented. The device is an unbalanced Mach Zehnder Interferometer (MZI) based on InP Membrane on Silicon (IMOS) platform. The MZI consists of a ferromagnetic thin-film cladding and a delay line in one branch, and a polarization converter in the other. It quantitatively measures the non-reciprocal phase shift caused by the Magneto-Optic Kerr Effect in the guided mode which depends on the memory bit’s magnetization direction. The current design is an analytical tool for research exploration of all-optical magnetic memory reading. It has been shown that the device is able to read a nanoscale memory bit (400 × 50 × 12 nm) by using a Kerr rotation as small as 0.2∘, in the presence of a noise ∼10 dB in terms of signal-to-noise ratio. The device is shown to tolerate performance reductions that can arise during the fabrication.

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Joshi, Aruna, G. S. Mukherjee, Mukul Gupta, and M. Banerjee. "Thickness dependent microstructural and magnetic studies of iron embedded PVA nanocomposite films." AIP Advances 13, no. 3 (March 1, 2023): 035339. http://dx.doi.org/10.1063/5.0125613.

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This paper presents the structural and magnetic properties of polyvinyl alcohol/iron (PVA/Fe) nanocomposite films. Iron (Fe) films of different thicknesses were deposited on a PVA substrate using ion beam sputtering. The Fe nanoparticle layer thickness ranges from 3 to 50 nm on the PVA substrate. Grazing incidence x-ray diffraction has been carried out to study the structural behavior of the prepared films. An atomic force microscope records the indicated remarkable change in the roughness of the nanocomposite film as a result of initiation of vertical growth of sputtered Fe nanoparticles.Magneto-optic Kerr effect (MOKE) magnetometry and MOKE spectroscopy have been employed to evaluate the magnetic property and simultaneously study the real time growth of the magnetic domain structure for both 0° and 90° azimuthal angles. MOKE microscopic images indicated the magnetization reversal commensurate with the hysteresis loop of the nanocomposites. All the films show soft ferromagnetic behavior. Gradual development of the domain structure is observed in the MOKE micrograph with the increase in the thickness of Fe nanoparticle deposition. Ex situ magnetic force micrographs of the magnetic domain structures supported the observation of MOKE microscopic studies, which indicated switching of in-plane magnetization to out-of-plane magnetization near an Fe nanoparticle deposition thickness of 40 nm. The PVA matrix appears to be an effective material to support the growth of magnetic properties in the PVA/Fe nanocomposite system. The evolution of Fe nanostructures on PVA and the resulting magnetic behavior have been discussed.

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Ehrmann, Andrea, and Tomasz Blachowicz. "Asymmetric Hysteresis Loops in Co Thin Films." Condensed Matter 5, no. 4 (November 5, 2020): 71. http://dx.doi.org/10.3390/condmat5040071.

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Asymmetric magnetic hysteresis loops are usually found in exchange bias (EB) systems, typically after field cooling a system below the Néel temperature of an antiferromagnet exchange coupled to a ferromagnet. Alternatively, asymmetric hysteresis loops may occur due to undetected minor loops or in systems with a rotational anisotropy. Here, we report on an exchange bias thin film system MgO(100)/Co/CoO, examined at room temperature, which is far above the blocking temperature, by the magneto-optical Kerr effect (MOKE). While the longitudinal hysteresis loops partly show steps which are well-known from diverse purely ferromagnetic systems, the transverse hysteresis loops exhibit clear asymmetries, similar to exchange biased systems at low temperatures, and unusual transverse magnetization values at saturation. Since minor loops and a rotational anisotropy can be excluded in this case, this asymmetry can possibly be a residue of the exchange bias coupling at lower temperatures.

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43

Deldar, Shayan, Marek Smaga, and Tilmann Beck. "Investigating the fatigue behavior of grain-oriented Fe-3%Si steel sheets using magnet-optical Kerr microscopy and micromagnetic multiparameter, microstructure and stress analysis." MATEC Web of Conferences 165 (2018): 06006. http://dx.doi.org/10.1051/matecconf/201816506006.

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Fatigue is considered as a reason for a significant number of mechanical failures of engineering materials. Conventionally, microstructural investigations along with stress-strain hysteresis measurements are performed to understand and characterize the fatigue behavior of metallic materials. Moreover, further physical data like temperature, electrical resistance and, in the case of ferromagnetic materials, magnetic properties can be used for a comprehensive characterization of fatigue process. The present work has employed Magneto-Optical Kerr Effect (MOKE) microscope and Micromagnetic Multiparameter, Microstructure and stress Analysis (3MA) system to illustrate magnetic domain structure and various intrinsic magnetic properties including magnetic Barkhausen noise (MBN) of the investigated material. In order to investigate the influence of the mechanical deformation processes on the magnetic parameters, samples were produced out of the grain-oriented electrical steel sheets and were subjected to a tensile test as well as a cyclic strain increase load test with R = 0 at ambient temperature.

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Chizhik, Alexander, Julian Gonzalez, Arkadi Zhukov, Andrzej Stupakiewicz, and Andrzej Maziewski. "Influence of Magnetic Field of Super High Frequency on Hysteretic Properties of Soft Magnetic Microwires." Advances in Science and Technology 93 (October 2014): 203–7. http://dx.doi.org/10.4028/www.scientific.net/ast.93.203.

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Normal 0 21 false false false MicrosoftInternetExplorer4 The influence of super high frequency (SHF) circular magnetic field on magnetization reversal in the Co-rich glass covered microwire has been investigated. The study has been performed by magneto-optical Kerr effect (MOKE) technique. It was found that the presence of the SHF field causes the change of the re-magnetization mechanism – the rotation of the magnetization is observed instead of domain walls motion. Also the hysteresis loop has an asymmetric shape that confirms the co-existence of the stable and meta-stable helical magnetic states in the surface of microwires. /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Tabla normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman"; mso-ansi-language:#0400; mso-fareast-language:#0400; mso-bidi-language:#0400;}

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45

Talantsev, Artem D., Ekaterina I. Kunitsyna, and Roman B. Morgunov. "The effect of Dzyaloshinskii–Moriya interaction on direct and backward transition between magnetic states of Pt/Co/Ir/Co/Pr synthetic ferrimagnet." Image Journal of Advanced Materials and Technologies 6, no. 3 (2021): 167–78. http://dx.doi.org/10.17277/jamt.2021.03.pp.167-178.

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In this paper, we present the study of domain structure accompanying interstate transitions in Pt/Co/Ir/Co/Pr synthetic ferrimagnet (SF) of 1.1 nm thick and 0.6 – 1.0 nm thin ferromagnetic Co layers. Variation in the thickness of the thin layer causes noticeable changes in the domain structure and mechanism of magnetization reversal revealed by MOKE (Magneto-Optical Kerr Effect) technique. Magnetization reversal includes coherent rotation of magnetization of the ferromagnetic layers, generation of magnetic nuclei, spreading of domain walls (DW), and development of areas similar with strip domains, dependently on thickness of the thin layer. Inequivalence of the direct and backward transitions between magnetic states of SF with parallel and antiparallel magnetizations was observed in sample with thin layer thicknesses 0.8 nm and 1.0 nm. Asymmetry of the transition between these states is expressed in difference fluctuation fields and shapes of reversal magnetization nucleus contributing to the correspondent forward and backward transitions. We proposed simple model based on asymmetry of Dzyaloshinskii–Moriya interaction. This model explains competition between nucleation and domain wall propagation due to increase/decrease of the DW energy dependently on direction of the spin rotation into the DW in respect to external field.

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Hu, Hai-Lin, Jia-Qi Yan, Wei Li, Xiao-Yu Yang, Shi-Tao Lou, and X. L. Zhang. "Gilbert Damping in Annealed Perpendicular Exchange Biased CoFeB/Pt/MnIr Multilayers." SPIN 10, no. 01 (March 2020): 2050008. http://dx.doi.org/10.1142/s2010324720500083.

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Exchange bias and intrinsic Gilbert damping [Formula: see text] are two important parameters in magnetic multilayers. To explore the correlation between exchange coupling and damping, the samples Ta (2.6[Formula: see text]nm)/Pt (2.5[Formula: see text]nm)/Co[Formula: see text]Fe[Formula: see text]B[Formula: see text] (0.63[Formula: see text]nm)/Pt (0.5[Formula: see text]nm)/Mn[Formula: see text]Ir[Formula: see text] ([Formula: see text])/Ta (4[Formula: see text]nm) are deposited by using pulsed-DC magnetron sputtering. The static and dynamic magnetic responses with different thickness of antiferromagnetic MnIr are investigated using vibrating sample magnetometer (VSM) and the pump-probe time-resolved magneto-optical Kerr effect (TR-MOKE). The exchange bias initially increases and then decreases with increasing thickness of MnIr layer, which is associated with the interfacial exchange coupling. The dynamic results demonstrate that the Gilbert damping of CoFeB/Pt/MnIr can increase by up to 40% compared with CoFeB/Pt. Based on the fact that the spin pumping has been excluded because of the Pt interlayer, we attribute the enhancement in Gilbert damping to the exchange coupling between AFM and FM.

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Kubota, Yuya, Hiroto Motoyama, Gota Yamaguchi, Satoru Egawa, Yoko Takeo, Masaki Mizuguchi, Himanshu Sharma, et al. "Scanning magneto-optical Kerr effect (MOKE) measurement with element-selectivity by using a soft x-ray free-electron laser and an ellipsoidal mirror." Applied Physics Letters 117, no. 4 (July 27, 2020): 042405. http://dx.doi.org/10.1063/5.0012348.

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Qiu, Z. Q., and S. D. Bader. "Surface magneto-optic Kerr effect." Review of Scientific Instruments 71, no. 3 (March 2000): 1243–55. http://dx.doi.org/10.1063/1.1150496.

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Qiu, Z. Q., and S. D. Bader. "Surface magneto-optic Kerr effect (SMOKE)." Journal of Magnetism and Magnetic Materials 200, no. 1-3 (October 1999): 664–78. http://dx.doi.org/10.1016/s0304-8853(99)00311-x.

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Hwang, Chan-Yong. "Understanding the Surface Magneto-optic Kerr Effect." Journal of the Korean Magnetics Society 21, no. 4 (August 31, 2011): 141–46. http://dx.doi.org/10.4283/jkms.2011.21.4.141.

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Journal articles on the topic 'Magneto-optic Kerr Effect (MOKE)'

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