Journal articles: 'Molecules - Magnetic properties'

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Tyagi, Pawan, Christopher D'Angelo, and Collin Baker. "Monte Carlo and Experimental Magnetic Studies of Molecular Spintronics Devices." Nano 10, no. 04 (June 2015): 1550056. http://dx.doi.org/10.1142/s1793292015500563.

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Molecule-based spintronics devices (MSDs) are highly promising candidates for discovering advanced logic and memory computer units. An advanced MSD will require the placement of paramagnetic molecules between the two ferromagnetic (FM) electrodes. Due to extreme fabrication challenges, only a couple of experimental studies could be performed to understand the effect of magnetic molecules on the overall magnetic and transport properties of MSDs. To date, theoretical studies mainly focused on charge and spin transport aspects of MSDs; there is a dearth of knowledge about the effect of magnetic molecules on the magnetic properties of MSDs. This paper investigates the effect of magnetic molecules, with a net spin, on the magnetic properties of 2D MSDs via Monte Carlo (MC) simulations. Our MC simulations encompass a wide range of MSDs that can be realized by establishing different kinds of magnetic interactions between molecules and FM electrodes at different temperatures. The MC simulations show that ambient thermal energy strongly influenced the molecular coupling effect on the MSD. We studied the nature and strength of molecule couplings (FM and antiferromagnetic) with the two electrodes on the magnetization, specific heat and magnetic susceptibility of MSDs. For the case when the nature of molecule interaction was FM with one electrode and antiferromagnetic with another electrode the overall magnetization shifted toward zero. In this case, the effect of molecules was also a strong function of the nature and strength of direct coupling between FM electrodes. In the case when molecules make opposite magnetic couplings with the two FM electrodes, the MSD model used for MC studies resembled with the magnetic tunnel junction based MSD. The experimental magnetic studies on these devices are in agreement with our theoretical MC simulations results. Our MC simulations will enable the fundamental understanding and designing of a wide range of novel spintronics devices utilizing a variety of molecules, nanoclusters and quantum dots as the device elements.

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Zlatanova, Jordanka, and Sanford H. Leuba. "Magnetic tweezers: a sensitive tool to study DNA and chromatin at the single-molecule level." Biochemistry and Cell Biology 81, no. 3 (June 1, 2003): 151–59. http://dx.doi.org/10.1139/o03-048.

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The advent of single-molecule biology has allowed unprecedented insight into the dynamic behavior of biological macromolecules and their complexes. Unexpected properties, masked by the asynchronous behavior of myriads of molecules in bulk experiments, can be revealed; equally importantly, individual members of a molecular population often exhibit distinct features in their properties. Finally, the single-molecule approaches allow us to study the behavior of biological macromolecules under applied tension or torsion; understanding the mechanical properties of these molecules helps us understand how they function in the cell. In this review, we summarize the application of magnetic tweezers (MT) to the study of DNA behavior at the single-molecule level. MT can be conveniently used to stretch DNA and introduce controlled levels of superhelicity into the molecule and to follow to a high definition the action of different types of topoisomerases. Its potential for chromatin studies is also enormous, and we will briefly present our first chromatin results.Key words: single-molecules, chromatin, topoisomerases, magnetic tweezers, force.

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Bader, Richard F. W., and Todd A. Keith. "Properties of atoms in molecules: Magnetic susceptibilities." Journal of Chemical Physics 99, no. 5 (September 1993): 3683–93. http://dx.doi.org/10.1063/1.466166.

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Schnack, Jürgen. "Frustration-induced exotic properties of magnetic molecules." Comptes Rendus Chimie 10, no. 1-2 (January 2007): 15–20. http://dx.doi.org/10.1016/j.crci.2006.07.010.

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Holmberg, Rebecca J., and Muralee Murugesu. "Adhering magnetic molecules to surfaces." Journal of Materials Chemistry C 3, no. 46 (2015): 11986–98. http://dx.doi.org/10.1039/c5tc03225c.

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In this review we aim to present an overview of the work that has been performed on attaching and studying Single-Molecule Magnets (SMMs) on various surfaces, with an emphasis on molecular design for surface interaction and on the magnetic properties before and after adhesion occurs.

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Lebedev, A. V. "Coagulation properties of a magnetic fluid stabilized with polydimethylsiloxane." Вестник Пермского университета. Физика, no. 4 (2020): 5–8. http://dx.doi.org/10.17072/1994-3598-2020-4-05-08.

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The stability of a stabilized with polydimethylsiloxane (PDMS) magnetic fluid to alcohols of a saturated homologous series was investigated. We used alcohols with a linear molecular structure and their possible isomers. It was found that the solubility of the PDMS stabilized particles strongly depends on the length of the coagulant molecules and, quite unexpectedly, on the degree of isomerization. The first tested coagulants, ethanol and acetone, did not mix with PDMS stabilized magnetic fluid. The next member of the homologous series, linear propanol, is an effective coagulant that causes a sharp precipitation of particles. Meanwhile, with isopropanol, coagulation occurs very smoothly. The butanol isomers differ even more. Normal butanol causes the liquid to coagulate at a higher concentration than propanol. Whereas tert-butanol is mixed with PDMS stabilized magnetic fluid in any proportion. The last linear alcohol in the homologous series that can serve as a coagulant is hexanol-1. The next members of the homologous series no longer mix with the PDMS stabilized magnetic fluid. This is typical only for linear molecules. For example, 2ethylhexanol (isooctanol) perfectly dissolves PDMS stabilized particles. This property can be used to separate mixtures of isomers and linear molecules.

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Keith, T. A., and R. F. W. Bader. "Properties of atoms in molecules: nuclear magnetic shielding." Canadian Journal of Chemistry 74, no. 2 (February 1, 1996): 185–200. http://dx.doi.org/10.1139/v96-022.

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This paper analyzes the nuclear magnetic shielding tensors underlying the chemical shift in NMR spectroscopy in terms of the field generated at the nucleus by the current J(1)(r) induced by an external magnetic field. The magnetic field at nucleus [Formula: see text] resulting from an element of the induced current density at a distance [Formula: see text] is proportional to [Formula: see text] which defines the shielding density [Formula: see text] The magnetic shielding of a nucleus is fundamentally an atomic property, a feature brought to the fore by using the theory of atoms in molecules and the integration of [Formula: see text] over the individual atomic basins relates the shielding tensor [Formula: see text] to a sum of atomic contributions. The shielding of nucleus ** is primarily determined by the flow of current within the basin of atom [Formula: see text], a contribution that varies from the approximate diamagnetic limit, given by the atomic Lamb value for the atom in the molecule, to values that are greatly reduced by the presence of paramagnetic current flows associated with particular bonding effects. Whether the contribution of a neighbouring atom is shielding or deshielding is readily understood by relating the form of the current flow within its basin to the magnetization density. [Formula: see text]. A study of the currents induced in benzene shows that the extent to which a proton, bonded to a ring of atoms, is deshielded by the field exerted by its bonded neighbour provides a direct diagnostic test for a ring current and an accurate relative measure of its strength. The theory of atoms in molecules isolates transferable atomic properties and because of this ability one finds, in addition to the anticipated result that a given functional group contributes identical amounts to the isotropic shielding [Formula: see text] of a nucleus external to it through a series of molecules, the more remarkable result that the whole of the variation in [Formula: see text] can have its origin in the basin of atom [Formula: see text], the contribution from external groups remaining constant. For example, the external contribution to [Formula: see text] for a carbon nucleus in a normal hydrocarbon is independent of chain length and position of [Formula: see text] within the chain, the methyl group in ethane contributing the same shielding to a methyl carbon as does the butyl group in pentane. This constancy in external contributions to the shielding is also found for N, O and F nuclei in substituted, saturated hydrocarbons. Key words: NMR, magnetic shielding, current density, magnetic shielding density.

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8

Naaman, Ron, and Zeev Vager. "Cooperative Electronic and Magnetic Properties of Self-Assembled Monolayers." MRS Bulletin 35, no. 6 (June 2010): 429–34. http://dx.doi.org/10.1557/mrs2010.580.

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AbstractSelf-assembled monolayers (SAMs) of organic dipolar molecules have new electronic and magnetic properties that result from their organization, despite the relatively weak interaction among the molecules themselves. Here we review the origin of this cooperative effect and summarize work performed on spin selective electron transmission through SAMs. The spin selectivity observed, in some cases, is consistent with a model in which a SAM containing chiral dipolar molecules behaves like a magnetic layer. The magnetic properties result in the SAMs behaving as spin filters, even without applying an external magnetic field to the layer.

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DE LA VENTA, J., E. FERNANDEZ PINEL, M. A. GARCIA, P. CRESPO, A. HERNANDO, O. RODRIGUEZ DE LA FUENTE, C. DE JULIÁN FERNÁNDEZ, A. FERNÁNDEZ, and S. PENADÉS. "MAGNETIC PROPERTIES OF ORGANIC COATED GOLD SURFACES." Modern Physics Letters B 21, no. 06 (March 10, 2007): 303–19. http://dx.doi.org/10.1142/s0217984907012761.

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We review here our recent results of experimental observation of room temperature magnetism in gold nanoparticles (NPs) and thin films. Capping gold surfaces with certain organic molecules leads to the appearance of magnetism at room temperature. The surface bonds between the organic molecules and Au atoms give rise to magnetic moments. These magnetic moments are blocked along the bond direction showing huge anisotropy. In the case of atomically flat surfaces, the magnetic moments are giants. An explanation of this orbital ferromagnetism is given. These results point out the possibility to observe magnetism at nanoscale in materials without typical magnetic atoms (transition metals and rare earths), and are of fundamental value to understand the magnetic properties of surfaces.

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Mínguez Espallargas, Guillermo, Mónica Giménez-Marqués, Néstor Calvo Galve, and Eugenio Coronado. "Responsive magnetic coordination polymers: effects of gas sorption." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C905. http://dx.doi.org/10.1107/s2053273314090949.

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Responsive materials for which physical or chemical properties can be tuned by applying an external stimulus are attracting considerable interest in view of their potential applications as chemical switches or molecular sensors [1]. A major source of such materials is provided by the so-called metal-organic frameworks (MOFs), in which physisorption of guest molecules, located in the pores, can cause subtle changes which affect the magnetic properties. Here we present two different approaches to modify the magnetic properties through gas sorption. First, we show that the chemisorption of gaseous HCl molecules by a non-porous one-dimensional coordination polymer instigates drastic modifications in the magnetic properties of the material, switching from strong antiferromagnets to ferromagnets upon gas sorption [2]. These conversions result from profound structural changes, involving cleavage and formation of covalent bonds caused by the removal/addition of ligands from the framework itself, but with no disruption of crystallinity. In a different approach, we present a family of FeII coordination polymers which shows spin-crossover behaviour and selectively sorbs CO2 over N2 [3]. Despite the lack of permanent channels, these non-porous coordination polymers trap CO2 gas molecules into the internal cavities due to the flexible and dynamic nature of the framework. One CO2 molecule is incorporated in each internal cavity of the crystalline material, as unequivocally demonstrated by structural determination after CO2 loading. This physisorption shifts the spin transition producing an increase in the transition temperature of 9 K (see Figure).

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11

Laskowski, Lukasz, Iwan Kityk, Piotr Konieczny, Oleksandr Pastukh, Mateusz Schabikowski, and Magdalena Laskowska. "The Separation of the Mn12 Single-Molecule Magnets onto Spherical Silica Nanoparticles." Nanomaterials 9, no. 5 (May 18, 2019): 764. http://dx.doi.org/10.3390/nano9050764.

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The Mn12 single-molecule magnets (SMMs) could be attached to the surface of spherical silica for the first time with a high probability. This allowed separation of the individual molecular magnets and direct microscopic observation of the SMMs. We described in detail how to fabricate such a composite material. The synthesis procedure proposed here is simple and efficient. We confirmed the efficiency of the method by transmission electron microscopy (TEM): single-molecule magnets were visible at the surface of a silica substrate. Based on TEM observation, we described how the molecules anchor to the surface of silica (the geometry of the magnetic molecule in regard to the surface of the substrate). The SQUID magnetometry showed that single-molecule magnet behaviour is kept intact after grafting. The attachment of the single-molecule magnets to the surface of silica allows to investigate their properties as separate molecules. This is particularly important in the analysis of magnetic properties such as magnetic states of the separated SMMs, their mutual interactions, and the influence of a silica support.

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12

Tyagi, Pawan. "Molecule Induced Strong Coupling between Ferromagnetic Electrodes of a Molecular Spintronics Device." Materials Science Forum 736 (December 2012): 32–54. http://dx.doi.org/10.4028/www.scientific.net/msf.736.32.

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Utilizing molecules for tailoring the exchange coupling strength between ferromagnetic electrodes can produce novel metamaterials and molecular spintronics devices (MSD). A practical way to produce such MSD is to connect the molecular channels to the electrodes of a magnetic tunnel junction (MTJ). This paper discusses the dramatic changes in the properties of MTJ testbed of a MSD due to molecular device elements with a net spin state. When organometallic molecular complexes (OMCs) were bridged across the insulator along the exposed side edges, a MTJ testbed exhibited entirely different magnetic response in magnetization, ferromagnetic resonance and magnetic force microscopy studies. OMCs only affected the ferromagnetic material when it was serving as the electrode of a tunnel junction. Molecule produced the strongest effect on the MTJ with electrodes of dissimilar magnetic hardness. This study encourages the validation of this work and exploration of similar observations with the other combinations MTJs and molecules, like single molecular magnet, porphyrin, and molecular clusters.

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13

Zhang, Lina, Shuyan Guan, Yunchang Fan, Chenxia Du, Dan Zhao, and Baozhong Liu. "Towards solvent tuning of slow magnetic relaxation and ferroelectric properties in a dysprosium metal–organic framework system." Zeitschrift für Kristallographie - Crystalline Materials 234, no. 1 (January 28, 2019): 33–41. http://dx.doi.org/10.1515/zkri-2018-2050.

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Abstract A new dysprosium metal–organic framework {[Dy2(L)3(H2O)4]·(acetone)2·(H2O)3}n (Dy2-Acetone) with single-molecule magnet and ferroelectric properties was synthesized through a solvent-induced single-crystal-to-single-crystal (SCSC) transformation. Notably, exchange of the coordinated and guest solvent molecules lead to different magnetic relaxation and ferroelectric properties in the dysprosium MOF system, Dy2-DMF and Dy2-Acetone. Study reveals that the tunable magnetic relaxation behaviors are most likely a result of different local coordination sphere and lattice solvent molecules within the pores which influenced and tuned the relaxation rates of the magnetization. Moreover, disparate polar solvent molecules confined in the MOFs may be the key factors for their different ferroelectric properties.

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14

Kudisch, Bryan, Margherita Maiuri, Luca Moretti, Maria B. Oviedo, Leon Wang, Daniel G. Oblinsky, Robert K. Prud’homme, Bryan M. Wong, Stephen A. McGill, and Gregory D. Scholes. "Ring currents modulate optoelectronic properties of aromatic chromophores at 25 T." Proceedings of the National Academy of Sciences 117, no. 21 (May 8, 2020): 11289–98. http://dx.doi.org/10.1073/pnas.1918148117.

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The properties of organic molecules can be influenced by magnetic fields, and these magnetic field effects are diverse. They range from inducing nuclear Zeeman splitting for structural determination in NMR spectroscopy to polaron Zeeman splitting organic spintronics and organic magnetoresistance. A pervasive magnetic field effect on an aromatic molecule is the aromatic ring current, which can be thought of as an induction of a circular current of π-electrons upon the application of a magnetic field perpendicular to the π-system of the molecule. While in NMR spectroscopy the effects of ring currents on the chemical shifts of nearby protons are relatively well understood, and even predictable, the consequences of these modified electronic states on the spectroscopy of molecules has remained unknown. In this work, we find that photophysical properties of model phthalocyanine compounds and their aggregates display clear magnetic field dependences up to 25 T, with the aggregates showing more drastic magnetic field sensitivities depending on the intermolecular interactions with the amplification of ring currents in stacked aggregates. These observations are consistent with ring currents measured in NMR spectroscopy and simulated in time-dependent density functional theory calculations of magnetic field-dependent phthalocyanine monomer and dimer absorption spectra. We propose that ring currents in organic semiconductors, which commonly comprise aromatic moieties, may present new opportunities for the understanding and exploitation of combined optical, electronic, and magnetic properties.

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15

Schmelcher, P., and L. S. Cederbaum. "Molecules in strong magnetic fields: Properties of atomic orbitals." Physical Review A 37, no. 3 (February 1, 1988): 672–81. http://dx.doi.org/10.1103/physreva.37.672.

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16

Schulman, Jerome M., and Raymond L. Disch. "Thermal and Magnetic Properties of Coronene and Related Molecules." Journal of Physical Chemistry A 101, no. 48 (November 1997): 9176–79. http://dx.doi.org/10.1021/jp972391i.

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17

Al-Saqer, M., V. V. Dobrovitski, B. N. Harmon, and M. I. Katsnelson. "Many-spin effects and tunneling properties of magnetic molecules." Journal of Applied Physics 87, no. 9 (May 2000): 6268–70. http://dx.doi.org/10.1063/1.372675.

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18

Keith, T. A., and R. F. W. Bader. "Calculation of magnetic response properties using atoms in molecules." Chemical Physics Letters 194, no. 1-2 (June 1992): 1–8. http://dx.doi.org/10.1016/0009-2614(92)85733-q.

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19

Sakaguchi, Kazuha, Biao Zhou, Yuki Idobata, Hajime Kamebuchi, and Akiko Kobayashi. "Syntheses, Structures, and Physical Properties of Neutral Gold Dithiolate Complex, [Au(etdt)2]·THF." Crystals 10, no. 11 (November 4, 2020): 1001. http://dx.doi.org/10.3390/cryst10111001.

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In order to develop new types of single-component molecular conductors with novel electronic structures and physical properties, the neutral gold dithiolate complex with an etdt (= ethylenedithiotetrathiafulvalenedithiolate) ligand, [Au(etdt)2] was prepared. However, unlike the reported single-component molecular metals, the neutral gold complex [Au(etdt)2]·THF (2) contains a solvent molecule of tetrahydrofuran (THF). The crystals of 2 form a two-dimensional conducting layer structure, which are separated by the terminal ethylene groups and THF molecules. The fairly high room-temperature conductivity of 0.2 S/cm and semiconducting behavior with a low activation energy of 0.1 eV of 2, is consistent with the result of the density functional theory band structure calculations. The observed non-magnetic behavior of 2 is caused from the dimeric structure of [Au(etdt)2] molecules.

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20

RAMAN, KARTHIK V., NICOLAE ATODIRESEI, and JAGADEESH S. MOODERA. "TAILORING FERROMAGNET–MOLECULE INTERFACES: TOWARDS MOLECULAR SPINTRONICS." SPIN 04, no. 02 (June 2014): 1440014. http://dx.doi.org/10.1142/s2010324714400141.

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Understanding the interaction of organic molecules adsorbed on magnetic surfaces has shown considerable progress in recent years. The creation of hybridized interface between carbon-based aromatic molecule and the magnetic surface is observed to give rise to new interface states with unique electronic and magnetic character. This study has opened up a molecular-design initiative to tailor the spin dependent electronic and magnetic functionalities of the hybrid interface. The purpose of this article is to provide a fundamental understanding of the spin-chemistry and spin-physics associated with the formation of such ferromagnet-molecule hybrid interfaces. We also discuss the recent progress in this field using state-of-the-art experiments and theoretical calculations with focus on the magnetic properties of the molecule and the magnetic surface. The study reveals several interesting interface phenomena: formation of induced molecular moment and exchange coupling with the magnetic surface, and molecular spin-filters. It also demonstrates significant changes in the magnetic anisotropy and inter-atomic magnetic exchange coupling of the magnetic surface. These studies open the possibilities of exploring new molecular functionalities toward further research in the subfield of interface-assisted molecular spintronics.

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21

Anh Tuan, Nguyen, Nguyen Huy Sinh, and Dam Hieu Chi. "Tailoring magnetic properties in Mn4 molecules: A way to develop single-molecule magnets." Journal of Applied Physics 109, no. 7 (April 2011): 07B105. http://dx.doi.org/10.1063/1.3545812.

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22

Horii, Yoji, Hal Suzuki, Yuji Miyazaki, Motohiro Nakano, Shota Hasegawa, Yoshifumi Hashikawa, and Yasujiro Murata. "Dynamics and magnetic properties of NO molecules encapsulated in open-cage fullerene derivatives evidenced by low temperature heat capacity." Physical Chemistry Chemical Physics 23, no. 17 (2021): 10251–56. http://dx.doi.org/10.1039/d1cp00482d.

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23

Wang, Bing-Wu, Zhe-Ming Wang, and Song Gao. "Organometallic Single-Ion Magnets." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C274. http://dx.doi.org/10.1107/s2053273314097253.

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The single-molecule magnets (SMMs) are attracting the increasing interesting due to their potential applications in high density information storage, quantum computing, molecular spintronics, and magnetic refrigeration. This field provides scientists a possible access into the crossover of the classical and quantum world, and a wonderful model to study the fascinating magnetic properties between microscopic and macroscopic materials, such as slow magnetization relaxation and quantum tunneling effect. After the milestone discovery of the first single-molecule magnets (SMMs) Mn12ac, many new SMMs were structurally and magnetically characterized. The most studied systems are mainly traditional coordination compounds with polynuclear structures. However, for the difficulties in the control of magnetic anisotropy and exchange coupling interactions of the cluster-type molecules, Mn12ac molecule is still one of the most important SMMs with the high relaxation barrier. From 2011 [1-3], we explored an organometallic sandwich molecule, Cp*ErCOT(Cp* = pentamethylcyclopenta-dienide; COT = cyclooctatetraenide), which behaves as a single-ion magnets, into the field of molecular nanomagnets. It opened a door of SMMs to the chemists in organometallic chemistry. Recently, we found some new sandwich or half-sandwich lanthanide organometallic molecules could also show the slow relaxation of magnetization. We hope these systems can provide new understandings of slow magnetic relaxation and new clues on the design and synthesis of molecular nanomagnets. This work was supported by NSFC, the National Basic Research Program of China.

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Cococcioni, Matteo, and Andrea Floris. "Magnetic Energy Landscape of Dimolybdenum Tetraacetate on a Bulk Insulator Surface." Applied Sciences 11, no. 9 (April 23, 2021): 3806. http://dx.doi.org/10.3390/app11093806.

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The magnetic states and the magnetic anisotropy barrier of a transition metal molecular complex, dimolybdenum tetraacetate, are investigated via density functional theory (DFT). Calculations are performed in the gas phase and on a calcite (10.4) bulk insulating surface, using the Generalized-Gradient Approximation (GGA)-PBE and the Hubbard-corrected DFT + U and DFT + U + V functionals. The molecular complex (denoted MoMo) contains two central metallic molybdenum atoms, embedded in a square cage of acetate groups. Recently, MoMo was observed to form locally regular networks of immobile molecules on calcite (10.4), at room conditions. As this is the first example of a metal-coordinated molecule strongly anchored to an insulator surface at room temperature, we explore here its magnetic properties with the aim to understand whether the system could be assigned features of a single molecule magnet (SMM) and could represent the basis to realize stable magnetic networks on insulators. After an introductory review on SMMs, we show that, while the uncorrected GGA-PBE functional stabilizes MoMo in a nonmagnetic state, the DFT + U and DFT + U + V approaches stabilize an antiferromagnetic ground state and several meta-stable ferromagnetic and ferrimagnetic states. Importantly, the energy landscape of magnetic states remains almost unaltered on the insulating surface. Finally, via a noncollinear magnetic formalism and a newly introduced algorithm, we calculate the magnetic anisotropy barrier, whose value indicates the stability of the molecule’s magnetic moment.

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Machata, Marek, Radovan Herchel, Ivan Nemec, and Zdeněk Trávníček. "Crystal structures and magnetic properties of two series of phenoxo-O bridged dinuclear Ln2 (Ln = Gd, Tb, Dy) complexes." Dalton Transactions 46, no. 46 (2017): 16294–305. http://dx.doi.org/10.1039/c7dt03441e.

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Flament, J. P., H. P. Gervais, and M. Rerat. "Gauge-dependent ket calculation of the magnetic properties of molecules." Journal of Molecular Structure: THEOCHEM 151 (May 1987): 39–60. http://dx.doi.org/10.1016/0166-1280(87)85043-1.

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Flament, J. P., H. P. Gervais, and M. Rérat. "Gauge-dependent ket calculation of the magnetic properties of molecules." Journal of Molecular Structure: THEOCHEM 164, no. 1-2 (February 1988): 121–34. http://dx.doi.org/10.1016/0166-1280(88)80010-1.

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Klar, David, Svetlana Klyatskaya, Andrea Candini, Bernhard Krumme, Kurt Kummer, Philippe Ohresser, Valdis Corradini, et al. "Antiferromagnetic coupling of TbPc2 molecules to ultrathin Ni and Co films." Beilstein Journal of Nanotechnology 4 (May 21, 2013): 320–24. http://dx.doi.org/10.3762/bjnano.4.36.

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The magnetic and electronic properties of single-molecule magnets are studied by X-ray absorption spectroscopy and X-ray magnetic circular dichroism. We study the magnetic coupling of ultrathin Co and Ni films that are epitaxially grown onto a Cu(100) substrate, to an in situ deposited submonolayer of TbPc2 molecules. Because of the element specificity of the X-ray absorption spectroscopy we are able to individually determine the field dependence of the magnetization of the Tb ions and the Ni or Co film. On both substrates the TbPc2 molecules couple antiferromagnetically to the ferromagnetic films, which is possibly due to a superexchange interaction via the phthalocyanine ligand that contacts the magnetic surface.

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Bustamante, Carlos, and Steven B. Smith. "Direct mechanical measurement of single DNA molecules through an optical microscope." Proceedings, annual meeting, Electron Microscopy Society of America 51 (August 1, 1993): 86–87. http://dx.doi.org/10.1017/s0424820100146278.

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Understanding the mechanical properties of DNA such as their bending and torsional rigidity can provide a great deal of insight about the factors that determine the folding of DNA during the cell cycle. These quantities have been obtained from bulk experiments using light scattering, equilibrium sedimentation, DNA cyclization, etc. Determination of the elastic properties of DNA with these methods is indirect, via a theoretical framework relating the observable quantities to the elastic parameters of the molecules. Moreover, the results represent an ensemble average over all accessible configurations of the molecule, with small contribution from stretched un-likely states.We have carried a systematic study of the elastic properties of single DNA molecules. Single DNA molecules were chemically attached by one end to a glass surface and by their other end to a magnetic bead. Equilibrium positions of the beads are observed in an optical microscope while the beads are acted on by known magnetic and hydrodynamic forces.

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Holmberg, Rebecca J., Ilia Korobkov, and Muralee Murugesu. "Enchaining EDTA-chelated lanthanide molecular magnets into ordered 1D networks." RSC Advances 6, no. 76 (2016): 72510–18. http://dx.doi.org/10.1039/c6ra09831b.

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Wu, Xiao-Lin, Ren-Shu Wang, Hui Yang, Jie Zhang, Ming-An Fu, Shi-Chao Fang, Xiao-Jia Chen, Yun Gao, and Zhong-Bing Huang. "Structural and Magnetic Properties of Potassium-Doped 2,3-DiMethylnaphthalene." Crystals 11, no. 6 (May 28, 2021): 608. http://dx.doi.org/10.3390/cryst11060608.

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The development of potential magnetic materials in metal-doped polycyclic aromatic hydrocarbons has been a research hotspot in recent years. Here we have successfully synthesized stable potassium-doped 2,3-dimethylnaphthalene samples. The combination of first-principles calculations and XRD results identifies that doping of potassium into 2,3-dimethylnaphthalene forms a monoclinic structure with a molar ratio of 1:2 between potassium and molecule. The red shifts in the Raman spectra indicate that potassium 4s electrons are transferred to the organic molecules. The magnetic measurements show that the doped materials exhibit a temperature-independent magnetization in the temperature region of 1.8–300 K, which is consistent with the Pauli paramagnetic behavior. This is distinct from the diamagnetism of pristine material. Compared to the previous focus on benzene ring structure, our study of aromatic hydrocarbon derivatives of benzene ring opens a new route for the development of this field.

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Caputo, M. C., M. B. Ferraro, P. Lazzeretti, M. Malagoli, and R. Zanasi. "Theoretical study of the magnetic properties of water molecules in non-uniform magnetic fields." Journal of Molecular Structure: THEOCHEM 305 (March 1994): 89–99. http://dx.doi.org/10.1016/0166-1280(94)80144-4.

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LUO, YUAN, LAN LUO, KAI SUN, MIN-LONG TAO, and JUN-ZHONG WANG. "STM STUDY OF THE ADSORPTION OF SINGLE-MOLECULE MAGNET Fe4 ON Bi(111) SURFACE." Surface Review and Letters 22, no. 05 (August 27, 2015): 1550060. http://dx.doi.org/10.1142/s0218625x15500602.

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Single-molecule magnets (SMMs) have unique magnetic properties such as quantum tunneling of magnetization and quantum coherent oscillation, which have potential applications in quantum computation and information storage. In this paper, using the tip-deposition method, we have grafted individual Fe 4 molecules onto the semi-metallic Bi (111) surface. Low temperature scanning tunneling microscope (LT-STM) was used to characterize the molecular morphology and electronic structures. It was found that individual Fe 4 molecules reveal a triangle shape, which is consistent with the molecular structure of Fe 4. Scanning tunneling spectroscopy (STS) analysis indicated that the HOMO–LUMO gap is 0.49 eV. These studies provide direct information about the adsorption of individual SMMs on semi-metal surfaces.

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Jiang, Y., G. Brunet, R. J. Holmberg, F. Habib, I. Korobkov, and M. Murugesu. "Terminal solvent effects on the anisotropy barriers of Dy2 systems." Dalton Transactions 45, no. 42 (2016): 16709–15. http://dx.doi.org/10.1039/c6dt03366k.

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A family of three dinuclear dysprosium complexes, all of which exhibit single-molecule magnet behaviour under zero applied dc fields, have exemplified that terminally bonded solvent molecules can drastically impact slow magnetic relaxation properties.

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Silva, Agnes Jalowitzki, Thaís F. Giacomello, Gunar V. da S. Mota, Antônio M. de J. Chaves, and Fabio L. P. Costa. "An Application of the Polarizable Continnum Model for Obtaining Chalcones Magnetic Properties." Advanced Science, Engineering and Medicine 12, no. 7 (July 1, 2020): 939–50. http://dx.doi.org/10.1166/asem.2020.2631.

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Chalcones exhibit a wide variety of beneficial biological activities. In addition, these compounds include the prevention of diseases related to oxidative stress. The structural characterization of these molecules by means of analytical techniques can become a difficult task due to the complexity of some structures. However, cases of erroneously established natural product structure review are still found in the literature despite recent advances in spectroscopic techniques. Therefore, it is necessary to develop quantum calculation protocols that can aid in the correct structural ascertainment of these compounds. Thus, in this work, we tried to develop a parameterized protocol for calculations of chemical shift of carbon-13 nuclear magnetic resonance, in order to ensure a correct structural determination of polyphenols, with a focus on chalcones. For this, a series of molecules belonging to this class, with complex and varied structural skeletons, reliably elucidated in the literature, was selected and subjected to stochastic conformational searches using the Monte Carlo method and the Merk molecular force filed. The lower energy conformations of each molecule were selected for the geometry optimization step, performed at the mPW1PW91/6-31G(d) level. The chemical shifts of carbon-13 were calculated at the same level of theory, taking into account the population distribution of Boltzmann. The calculations were affected in both liquid phases, using the Polarizable Continuous Model as an implicit solvation model. The results show that the level of theory applied in the liquid phase allows a good reproduction of the experimental data. The application of the scaling factor allows the cancellation of systematic errors, which means that the values of scaled chemical shift are closer to the experimental ones. Thus, the parameterized protocol proved to be an important tool for the structural elucidation of polyphenols by calculations of carbon-13 nuclear magnetic resonance chemical shifts.

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Liu, Ping, Jia Cheng Liu, Jian Wang, Jian Kai Cheng, Wen Jie Li, and Xin Huang. "Magnetic properties of some FeS six-membered ring compounds." Canadian Journal of Chemistry 80, no. 12 (December 1, 2002): 1646–49. http://dx.doi.org/10.1139/v02-184.

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The Fe3S3 cluster is an important component located in the active centres of some ironsulfur proteins. The magnetic properties of three Fe3S3 compounds have been studied for the first time by fitting the temperature-dependent magnetic susceptibilities. The calculated g factors and J couplings reproduce the magnetic behavior of such compounds very well. There is an antiferromagnetic spin interaction between pairs of magnetic centers in the Fe3S3 cluster compounds. The magnetic exchange of Fe-S-Fe model magnetic molecules is discussed.Key words: Fe3S3 compounds, magnetic, antiferromagnetic.

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Awaga, Kunio, Eugenio Coronado, and Marc Drillon. "Hybrid Organic/Inorganic Magnets." MRS Bulletin 25, no. 11 (November 2000): 52–57. http://dx.doi.org/10.1557/mrs2000.224.

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The construction of more and more complex systems starting from elemental molecular units used as building blocks is propelling several disciplines of burgeoning interest, such as supramolecular chemistry, molecular electronics, and molecular magnetism. In the particular context of magnetic molecular materials, an attractive possibility for adding complexity to the material is to use a hybrid approach in which an organic component is combined with an inorganic one. Both purely organic and purely inorganic approaches (see the articles in this issue by Veciana and Iwamura and by Miller, respectively) have been used extensively to obtain molecule-based magnets. The combination of these two kinds of magnetic molecular components has also been successfully explored to design polymeric magnets of different dimensionalities (the metal-radical approach). In this last case, both components play a magnetic role. A step forward in achieving multifunctionality is to design hybrid molecular materials formed by two independent molecular networks, such as anion/cation salts or host/guest solids, whereby each network furnishes distinct physical properties to the solid. This novel class of materials is interesting because it can give rise to the development of materials in which two properties in the same crystal lattice coexist, or materials that exhibit improved properties over those of the individual networks, or to new, unexpected properties due to the mutual interactions between them. One can imagine, for example, the combination of an extended inorganic magnetic layer opening the pathway to cooperative magnetism, with an organic or organometallic molecule that acts as a structural component controlling the interlayer separation. If the molecule inserted between the layers has unpaired electrons, a hybrid compound is produced that combines cooperative magnetism and paramagnetism. Other suitable combinations, such as electronic conductivity and magnetism, or nonlinear optics and magnetism, can also be achieved by wisely choosing the constituent molecules. In this article, we report some relevant examples that illustrate the potential of this hybrid approach in the context of molecule-based magnetic materials.

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Leniec, G., Slawomir M. Kaczmarek, J. Typek, Beata Kołodziej, Eugeniusz Grech, and W. Schilf. "Spectroscopic and Magnetic Properties of Gadolinium Macroacyclic and Macrobicyclic Complexes." Solid State Phenomena 128 (October 2007): 199–205. http://dx.doi.org/10.4028/www.scientific.net/ssp.128.199.

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As a result of the Schiff base condensation the gadolinium macroacyclic and macrobicyclic Schiff base complexes have been synthesized and investigated by infrared spectroscopy (IR) and electron paramagnetic resonance (EPR). Both electron ionization and electron spray Molecular Spectroscopy spectra confirmed the [1:1] proportion of a ligand to metal in gadolinium macrocyclic and mocrobicyclic Schiff base complex samples. The thermogravimetrydifferential thermal analysis (TG-DTA) indicated the presence of two water molecules in the innersphere of the macrobicyclic complex and confirmed no water coordination of the metal ion in the macroacyclic complex. The temperature dependence of the integrated intensity of the EPR spectra enabled the magnetic interactions in the spin system of these compounds to be revealed.

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Belkhiri, Lotfi, Boris Le Guennic, and Abdou Boucekkine. "DFT Investigations of the Magnetic Properties of Actinide Complexes." Magnetochemistry 5, no. 1 (February 17, 2019): 15. http://dx.doi.org/10.3390/magnetochemistry5010015.

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Over the past 25 years, magnetic actinide complexes have been the object of considerable attention, not only at the experimental level, but also at the theoretical one. Such systems are of great interest, owing to the well-known larger spin–orbit coupling for actinide ions, and could exhibit slow relaxation of the magnetization, arising from a large anisotropy barrier, and magnetic hysteresis of purely molecular origin below a given blocking temperature. Furthermore, more diffuse 5f orbitals than lanthanide 4f ones (more covalency) could lead to stronger magnetic super-exchange. On the other hand, the extraordinary experimental challenges of actinide complexes chemistry, because of their rarity and toxicity, afford computational chemistry a particularly valuable role. However, for such a purpose, the use of a multiconfigurational post-Hartree-Fock approach is required, but such an approach is computationally demanding for polymetallic systems—notably for actinide ones—and usually simplified models are considered instead of the actual systems. Thus, Density Functional Theory (DFT) appears as an alternative tool to compute magnetic exchange coupling and to explore the electronic structure and magnetic properties of actinide-containing molecules, especially when the considered systems are very large. In this paper, relevant achievements regarding DFT investigations of the magnetic properties of actinide complexes are surveyed, with particular emphasis on some representative examples that illustrate the subject, including actinides in Single Molecular Magnets (SMMs) and systems featuring metal-metal super-exchange coupling interactions. Examples are drawn from studies that are either entirely computational or are combined experimental/computational investigations in which the latter play a significant role.

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Xu, Hailong, Hong Zhou, Lu Feng, Qiaoyun Wang, Rui Chen, Wentao Huang, and Xixi Wu. "Synthesis, crystal structures, and magnetic properties of six transition metal phosphonates." Dalton Transactions 47, no. 32 (2018): 11226–38. http://dx.doi.org/10.1039/c8dt02070a.

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Crippa, Luca, Francesco Tacchino, Mario Chizzini, Antonello Aita, Michele Grossi, Alessandro Chiesa, Paolo Santini, Ivano Tavernelli, and Stefano Carretta. "Simulating Static and Dynamic Properties of Magnetic Molecules with Prototype Quantum Computers." Magnetochemistry 7, no. 8 (August 12, 2021): 117. http://dx.doi.org/10.3390/magnetochemistry7080117.

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Magnetic molecules are prototypical systems to investigate peculiar quantum mechanical phenomena. As such, simulating their static and dynamical behavior is intrinsically difficult for a classical computer, due to the exponential increase of required resources with the system size. Quantum computers solve this issue by providing an inherently quantum platform, suited to describe these magnetic systems. Here, we show that both the ground state properties and the spin dynamics of magnetic molecules can be simulated on prototype quantum computers, based on superconducting qubits. In particular, we study small-size anti-ferromagnetic spin chains and rings, which are ideal test-beds for these pioneering devices. We use the variational quantum eigensolver algorithm to determine the ground state wave-function with targeted ansatzes fulfilling the spin symmetries of the investigated models. The coherent spin dynamics are simulated by computing dynamical correlation functions, an essential ingredient to extract many experimentally accessible properties, such as the inelastic neutron cross-section.

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HALLBERG, K., JULIAN RINCON, and S. RAMASESHA. "QUANTUM PROPERTIES IN TRANSPORT THROUGH NANOSCOPIC RINGS: CHARGE-SPIN SEPARATION AND INTERFERENCE EFFECTS." International Journal of Modern Physics B 24, no. 25n26 (October 20, 2010): 5068–78. http://dx.doi.org/10.1142/s0217979210057213.

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Many of the most intriguing quantum effects are observed or could be measured in transport experiments through nanoscopic systems such as quantum dots, wires and rings formed by large molecules or arrays of quantum dots. In particular, the separation of charge and spin degrees of freedom and interference effects have important consequences in the conductivity through these systems. Charge-spin separation was predicted theoretically in one-dimensional strongly interacting systems (Luttinger liquids) and, although observed indirectly in several materials formed by chains of correlated electrons, it still lacks direct observation. We present results on transport properties through Aharonov-Bohm rings (pierced by a magnetic flux) with one or more channels represented by paradigmatic strongly-correlated models. For a wide range of parameters we observe characteristic dips in the conductance as a function of magnetic flux which are a signature of spin and charge separation. Interference effects could also be controlled in certain molecules and interesting properties could be observed. We analyze transport properties of conjugated molecules, benzene in particular, and find that the conductance depends on the lead configuration. In molecules with translational symmetry, the conductance can be controlled by breaking or restoring this symmetry, e.g. by the application of a local external potential. These results open the possibility of observing these peculiar physical properties in anisotropic ladder systems and in real nanoscopic and molecular devices.

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Dressel, M., M. Dumm, T. Knoblauch, B. Köhler, B. Salameh, and S. Yasin. "Charge Order Breaks Magnetic Symmetry in Molecular Quantum Spin Chains." Advances in Condensed Matter Physics 2012 (2012): 1–13. http://dx.doi.org/10.1155/2012/398721.

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Charge order affects most of the electronic properties but is believed not to alter the spin arrangement since the magnetic susceptibility remains unchanged. We present electron-spin-resonance experiments on quasi-one-dimensional(TMTTF)2Xsalts (X=PF6, AsF6, and SbF6), which reveal that the magnetic properties are modified belowTCOwhen electronic ferroelectricity sets in. The coupling of anions and organic molecules rotates the g-tensor out of the molecular plane creating magnetically nonequivalent sites on neighboring chains at domain walls. Due to anisotropic Zeeman interaction a novel magnetic interaction mechanism in the charge-ordered state is observed as a doubling of the rotational periodicity ofΔH.

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Palii, Andrew, Juan M. Clemente-Juan, Boris Tsukerblat, and Eugenio Coronado. "Electric field control of the optical properties in magnetic mixed-valence molecules." Chem. Sci. 5, no. 9 (2014): 3598–602. http://dx.doi.org/10.1039/c4sc01056f.

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Mun, Eundeok, Jason Wilcox, Jamie L. Manson, Brian Scott, Paul Tobash, and Vivien S. Zapf. "The Origin and Coupling Mechanism of the Magnetoelectric Effect inTMCl2-4SC(NH2)2(TM= Ni and Co)." Advances in Condensed Matter Physics 2014 (2014): 1–4. http://dx.doi.org/10.1155/2014/512621.

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Most research on multiferroics and magnetoelectric effects to date has focused on inorganic oxides. Molecule-based materials are a relatively new field in which to search for magnetoelectric multiferroics and to explore new coupling mechanisms between electric and magnetic order. We present magnetoelectric behavior in NiCl2-4SC(NH2)2(DTN) and CoCl2-4SC(NH2)2(DTC). These compounds form tetragonal structures where the transition metal ion (Ni or Co) is surrounded by four electrically polar thiourea molecules [SC(NH2)2]. By tracking the magnetic and electric properties of these compounds as a function of magnetic field, we gain insights into the coupling mechanism by observing that, in DTN, the electric polarization tracks the magnetic ordering, whereas in DTC it does not. For DTN, all electrically polar thiourea molecules tilt in the same direction along thec-axis, breaking spatial-inversion symmetry, whereas, for DTC, two thiourea molecules tilt up and two tilt down with respect toc-axis, perfectly canceling the net electrical polarization. Thus, the magnetoelectric coupling mechanism in DTN is likely a magnetostrictive adjustment of the thiourea molecule orientation in response to magnetic order.

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Dougherty, Dennis A., and David A. Kaisaki. "New Designs for Organic Molecules and Materials with Novel Magnetic Properties." Molecular Crystals and Liquid Crystals Incorporating Nonlinear Optics 183, no. 1 (January 1990): 71–79. http://dx.doi.org/10.1080/15421409008047442.

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Nikiforov, V. N., V. D. Kuznetsov, Yu M. Yevdokimov, and V. Yu Irkhin. "Magnetic properties of Gd3+ ions in the spatially distributed DNA molecules." Journal of Magnetism and Magnetic Materials 368 (November 2014): 338–41. http://dx.doi.org/10.1016/j.jmmm.2014.06.008.

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Wei, Wei, Fu-quan Bai, Bao-hui Xia, Hai-bo Chen, and Hong-xing Zhang. "Theoretical analysis on magnetic properties of conjugated organic molecules containing borepin." Chemical Research in Chinese Universities 29, no. 5 (September 14, 2013): 962–68. http://dx.doi.org/10.1007/s40242-013-3129-0.

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Rossikhin, V. V., E. O. Voronkov, and V. V. Kuzmenko. "Magnetic properties of molecules with Gauss-type function depending on perturbation." Journal of Magnetism and Magnetic Materials 104-107 (February 1992): 2127–28. http://dx.doi.org/10.1016/0304-8853(92)91696-q.

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Friedrich, Břetislav, and Dudley R. Herschbach. "Thermodynamic Functions of Pendular Molecules." Collection of Czechoslovak Chemical Communications 58, no. 10 (1993): 2458–73. http://dx.doi.org/10.1135/cccc19932458.

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External electric or magnetic fields can hybridize rotational states of individual dipolar molecules and thus create pendular states whose field-dependent eigenproperties differ qualitatively from those of a rotor or an oscilator. The pendular eigenfunctions are directional, so the molecular axis id oriented. Here we use quantum statistical mechanics to evaluate ensamble properties of the pendular states. For linear molecules, the partition function and the averages that determine the thermodynamic functions can be specified by two reduced variables involving the dipole moment, field strength, rotational constant, and temperature. We examine a simple approximation due to Pitzer that employs the classical partition function with quantum corrections. This provides explicit analytic formulas which permit thermodynamic properties to be evaluated to good accuracy without computing energy levels. As applications we evaluate the high-field average orientation of the molecular dipoles and field-induced shifts of chemical equilibria.

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Journal articles on the topic 'Molecules - Magnetic properties'

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