Academic literature on the topic 'Magnetos moleculares'
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Journal articles on the topic "Magnetos moleculares"
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Awaga, Kunio, Eugenio Coronado, and Marc Drillon. "Hybrid Organic/Inorganic Magnets." MRS Bulletin 25, no. 11 (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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Dubrovin, Vasilii, Alexey A. Popov, and Stanislav Avdoshenko. "Magnetism in Ln molecular systems with 4f/valence-shell interplay (FV-magnetism)." Chemical Communications 55, no. 93 (2019): 13963–66. http://dx.doi.org/10.1039/c9cc06913e.
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The hunt for high-performance single-molecule magnets (SMM) revealed that lanthanide systems combining 4f- and valence-shells show magnetic bistability up to very high temperatures. We rationalize magnetism in such systems from first principles.
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Epstein, Arthur J. "Organic-Based Magnets: Opportunities in Photoinduced Magnetism, Spintronics, Fractal Magnetism, and Beyond." MRS Bulletin 28, no. 7 (2003): 492–99. http://dx.doi.org/10.1557/mrs2003.145.
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AbstractThis article is based on a presentation on organic-based magnets given as part of Symposium X—Frontiers of Materials Research on December 4, 2002, at the 2002 Materials Research Society Fall Meeting in Boston. The advent of organic-based magnets opened the opportunity for tuning magnetic properties by molecular design and the discovery of new phenomena that rely on the internal structure of the molecules that make up these magnets. In the past 18 years, numerous classes of organic-based ferromagnets, ferrimagnets, and spin glasses (spins essentially frozen in place without long-range order) have been reported. These materials have magnetic ordering temperatures ranging from <1 K to above room temperature and demonstrate many of the magnetic properties associated with conventional magnets. This article concentrates on new phenomena that are unique to organic-based magnets. Three of these effects—“high-temperature” light-induced magnetism, spin-polarized magnetic organic semiconductors with the potential for spintronics, and the development of fractal magnetic order—are discussed to illustrate the richness of opportunity in organic-based magnets.
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Blachowicz, Tomasz, and Andrea Ehrmann. "New Materials and Effects in Molecular Nanomagnets." Applied Sciences 11, no. 16 (2021): 7510. http://dx.doi.org/10.3390/app11167510.
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Molecular magnets are a relatively new class of purely organic or metallo-organic materials, showing magnetism even without an external magnetic field. This interdisciplinary field between chemistry and physics has been gaining increased interest since the 1990s. While bulk molecular magnets are usually hard to build because of their molecular structures, low-dimensional molecular magnets are often easier to construct, down to dot-like (zero-dimensional) structures, which are investigated by different scanning probe technologies. On these scales, new effects such as superparamagnetic behavior or coherent switching during magnetization reversal can be recognized. Here, we give an overview of the recent advances in molecular nanomagnets, starting with single-molecule magnets (0D), typically based on Mn12, Fe8, or Mn4, going further to single-chain magnets (1D) and finally higher-dimensional molecular nanomagnets. This review does not aim to give a comprehensive overview of all research fields dealing with molecular nanomagnets, but instead aims at pointing out diverse possible materials and effects in order to stimulate new research in this broad field of nanomagnetism.
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Etcheverry-Berrios, Alvaro, Simon Parsons, Konstantin V. Kamenev, et al. "Putting the Squeeze on Molecule-Based Magnets: Exploiting Pressure to Develop Magneto-Structural Correlations in Paramagnetic Coordination Compounds." Magnetochemistry 6, no. 3 (2020): 32. http://dx.doi.org/10.3390/magnetochemistry6030032.
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The cornerstone of molecular magnetism is a detailed understanding of the relationship between structure and magnetic behaviour, i.e., the development of magneto-structural correlations. Traditionally, the synthetic chemist approaches this challenge by making multiple compounds that share a similar magnetic core but differ in peripheral ligation. Changes in the ligand framework induce changes in the bond angles and distances around the metal ions, which are manifested in changes to magnetic susceptibility and magnetisation data. This approach requires the synthesis of a series of different ligands and assumes that the chemical/electronic nature of the ligands and their coordination to the metal, the nature and number of counter ions and how they are positioned in the crystal lattice, and the molecular and crystallographic symmetry have no effect on the measured magnetic properties. In short, the assumption is that everything outwith the magnetic core is inconsequential, which is a huge oversimplification. The ideal scenario would be to have the same complex available in multiple structural conformations, and this is something that can be achieved through the application of external hydrostatic pressure, correlating structural changes observed through high-pressure single crystal X-ray crystallography with changes observed in high-pressure magnetometry, in tandem with high-pressure inelastic neutron scattering (INS), high-pressure electron paramagnetic resonance (EPR) spectroscopy, and high-pressure absorption/emission/Raman spectroscopy. In this review, which summarises our work in this area over the last 15 years, we show that the application of pressure to molecule-based magnets can (reversibly) (1) lead to changes in bond angles, distances, and Jahn–Teller orientations; (2) break and form bonds; (3) induce polymerisation/depolymerisation; (4) enforce multiple phase transitions; (5) instigate piezochromism; (6) change the magnitude and sign of pairwise exchange interactions and magnetic anisotropy, and (7) lead to significant increases in magnetic ordering temperatures.
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Ma, Rende, Luxue Wan, Xiuhao Liu, Xiaoping Li, Junfeng Jiang, and Yunjie Xia. "Polarization in D-shaped fiber modulated by magneto-optical dichroism of magnetic fluid." Chinese Optics Letters 18, no. 1 (2020): 010601. http://dx.doi.org/10.3788/col202018.010601.
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Al Ma’Mari, Fatma, Matthew Rogers, Shoug Alghamdi, et al. "Emergent magnetism at transition-metal–nanocarbon interfaces." Proceedings of the National Academy of Sciences 114, no. 22 (2017): 5583–88. http://dx.doi.org/10.1073/pnas.1620216114.
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Charge transfer at metallo–molecular interfaces may be used to design multifunctional hybrids with an emergent magnetization that may offer an eco-friendly and tunable alternative to conventional magnets and devices. Here, we investigate the origin of the magnetism arising at these interfaces by using different techniques to probe 3d and 5d metal films such as Sc, Mn, Cu, and Pt in contact with fullerenes and rf-sputtered carbon layers. These systems exhibit small anisotropy and coercivity together with a high Curie point. Low-energy muon spin spectroscopy in Cu and Sc–C60 multilayers show a quick spin depolarization and oscillations attributed to nonuniform local magnetic fields close to the metallo–carbon interface. The hybridization state of the carbon layers plays a crucial role, and we observe an increased magnetization as sp3 orbitals are annealed into sp2−π graphitic states in sputtered carbon/copper multilayers. X-ray magnetic circular dichroism (XMCD) measurements at the carbon K edge of C60 layers in contact with Sc films show spin polarization in the lowest unoccupied molecular orbital (LUMO) and higher π*-molecular levels, whereas the dichroism in the σ*-resonances is small or nonexistent. These results support the idea of an interaction mediated via charge transfer from the metal and dz–π hybridization. Thin-film carbon-based magnets may allow for the manipulation of spin ordering at metallic surfaces using electrooptical signals, with potential applications in computing, sensors, and other multifunctional magnetic devices.
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Wang, Bing-Wu, Xin-Yi Wang, Hao-Ling Sun, Shang-Da Jiang, and Song Gao. "Evolvement of molecular nanomagnets in China." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 371, no. 2000 (2013): 20120316. http://dx.doi.org/10.1098/rsta.2012.0316.
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Molecular nanomagnets have been undergoing development for 20 years since the first single-molecule magnet (SMM), Mn 12 Ac, was characterized as the molecule-behaved magnet. The multi-disciplinary scientists promoted the magnetic characteristics to be more suitable for use in information science and spintronics. The concept of molecular nanomagnets has also evolved to include single-chain magnets (SCMs), single-ion magnets (SIMs) and even magnetic molecules that showed only slow magnetic relaxation, in addition to the initial cluster-type SMMs. In this review, several aspects, including SMMs, SCMs and SIMs, are introduced briefly through some representative examples. In particular, the contribution of Chinese chemists is highlighted in the design, synthesis and understanding of various types of molecular nanomagnets.
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Pyalling, A. A., and N. S. Ovanesyan. "Magnetic relaxation in two-dimensional molecular magnets." Bulletin of the Russian Academy of Sciences: Physics 71, no. 9 (2007): 1310–13. http://dx.doi.org/10.3103/s1062873807090262.
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Sugano, Tadashi, F. L. Pratt, M. Kurmoo, et al. "Magnetic ordering in some organic molecular magnets." Synthetic Metals 71, no. 1-3 (1995): 1827–28. http://dx.doi.org/10.1016/0379-6779(94)03070-m.
Full textDissertations / Theses on the topic "Magnetos moleculares"
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Cruz, Clebson dos Santos. "Propriedades Magnéticas de Magnetos Moleculares." Niterói, 2017. https://app.uff.br/riuff/handle/1/4020.
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DissertaçãoClebson.pdf: 4945486 bytes, checksum: 38749676f1117adb73bf8a84b5f8989b (MD5)<br>Coordenação de Aperfeiçoamento de Pessoal de Nível Superior<br>Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro<br>Com o desenvolvimento de novas tecnologias e os avanços nas técnicas de preparação de materiais, uma grande variedade de novos compostos puderam então ser sintetizados, dentre estes compostos estão os Magnetos Moleculares. Neste texto, apresentamos alguns fundamentos do magnetismo molecular, destacando o processo de construção de modelos para a descrição do comportamento magnético destes materiais através do ajuste dos dados da susceptibilidade magnética em função da temperatura. Buscamos compreender a maneira com que os diferentes parâmetros químicos e estruturais e afetam os mecanismos físicos que governam estes sistemas através do estudo de três séries de magnetos moleculares: um polímero bidimesional de Mn(II) sintetizado a partir do ácido 2,6-diclorobenzóico (C7H4Cl2O2), cujos parâmetros otimizados obtidos através do modelo sugerem que este composto possui um caráter global antiferromagnético; uma série de quatro compostos polinucleares de Cu(II) sintetizados com adenina (C5H5N5), cluster hexagonal heptanuclear ferromagnético e três cadeias antiferromagnéticas 2D dinucleares; uma série de quatro estruturas Metal-Orgânicas (Metal organic Frameworks-MOF) de Cu(II)-piperazina, onde foi feito um mapa das possíveis interações magnéticas para cada amostra. Por fim, como perspectiva para este trabalho pretendemos dar continuidade ao estudo de sistemas de magnetos moleculares dando ênfase à aplicação em informação quântica.<br>From the development of new technologies and advances in materials preparation techniques a wide variety of new compounds could be synthesized, among these compounds are the Molecular Magnets. In this paper, we present some fundamentals of molecular magnetism, highlighting the model-building process for the description of the magnetic behavior of these materials by fitting of the magnetic susceptibility as a function of temperature. Our goal is to understand how different chemical and structural parameters can affect the physical mechanisms that govern these systems . To achieve our aim we study three series of molecular magnets: a two-dimensional polymer Mn(II) synthesized from 2,6-acid dichlorobenzoic (C7H4Cl2O2), the optimized parameters obtained from the model suggest that this compound has an antiferromagnetic global character; a series of four polynuclear compounds of Cu(II) synthesized with adenine (C5H5N5), a ferromagnetic hexagonal cluster and three antiferromagnetic 2 D chains; a series of four Metal-Organic Frameworks (MOF) of Cu(II) -piperazine, where a magnetic interaction map was done for each sample. Finally, the perspective we intend to emphasize the study of molecular magnets systems with applications in quantum information.
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Dutra, Rangel Caio Quinino. "Magnetos moleculares de baixa dimensionalidade baseados em ligantes oxamato." Universidade Federal de Minas Gerais, 2008. http://hdl.handle.net/1843/BIRC-86EMC2.
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O presente trabalho trata da química e magnetismo de sistemas moleculares de baixa dimensionalidade. Inicialmente são descritos experimentos para a obtenção e caracterização de uma nova fase cristalina do composto [4-MeRad]2[Mn2{Cu(opba)}3], que apresenta fenômenos magnéticos não observados na literatura, como a Tc em torno de 13-15 K e um efeito de metamagnetismo induzido pela presença de excesso de solvente no composto. Foram estudados os compostos [4-MeRad]2[Mn2{Cu(opba)}3].5DMSO.2H2O e [4-MeRad]2[Mn2{Cu(opba)}3].4DMSO. 2H2O. Medidas de suscetibilidade AC nesse composto não apresentaram dependência com a freqüência. Apesar de ser verificada a abertura das curvas FCM e ZFCM em baixa temperatura, também verificou-se que curva da dependência da magnetização com o campo aplicado não apresenta histerese perceptível. Os valores de e da magnetização de saturação, se apresentaram próximos aos valores esperados para este sistema. Também é descrita a síntese com Fe2+, resultando na obtenção do composto Fe3Cu2(opba)3.9H2O, que apresenta um acoplamento antiferromagnético muito intenso revelado pelo valor de de 6,7 emu K mol-1 na tempertura do ambiente, indicando que nesta temperatura já há o efeito de cooperação antiferromagnética entre os spins do sistema. Na seqüência é estudada a influência da adição de cátions derivados do imidazol na química e magnetismo de sistemas constituídos por Cu(opba) e manganês. Foram obtidos e caracterizados os compostos inéditos IMes2Cu(opba).3H2O e IPr2Cu(opba).3H2O. O segundo apresentou um comportamento diamagnético, incomum para sistemas com o íon metálico Cu2+ em sua estrutura. Finalmente são descritos os procedimentos de inclusão de um segundo íon metálico (manganês e cobalto) que culminaram com a obtenção e caracterização do composto (IMes)2Mn{Cu(opba)}2.4H2O em que acredita-se que os grupos mesitil tenham sido capazes de evitar a coordenação nas carbonilas do opba, evitando assim o processo de polimerização.
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Alves, Álvaro Santos. "Estudo de magnetos moleculares através de cálculos de primeiros princípios." Niterói, 2017. https://app.uff.br/riuff/handle/1/3966.
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tese.pdf: 4548404 bytes, checksum: f3c3be1c9d5bbc0d098d37be6674bd4b (MD5)<br>Coordenação de Aperfeiçoamento de Pessoal de Nível Superior<br>Universidade Estadual de Feira de Santana<br>Neste trabalho, utilizamos cálculos de primeiros princípios baseados na Teoria do Funcional da Densidade (DFT - Density Functional Theory) para investigar a estabilidade energética e as propriedades magnéticas de compostos químicos. Foram estudados os complexos com metais de transição contendo radicais do tipo nitronilnitróxido [M(II)(Phtfac)2(NITpPy)2] [M = Co, Mn] e [M(II)(NITmPy)2(DMSO)2] [M = Cu, Ni, Co], bem como o silicato de cobre Na2Cu5(Si2O7)2. A partir do cálculo da energia total, determinamos a configuração de equilíbrio para os cinco complexos metálicos e os valores das constantes de acoplamento. Além disso, foram obtidas também as respectivas distribuições de densidade de magnetização, fundamentais para entender os mecanismos de acoplamento magnético nesse tipo de sistema. Para o silicato de cobre, cujos responsáveis pelas propriedades magnéticas são cadeias alternadas de trímeros e dímeros, calculamos a energia total das 32 configurações possíveis; determinamos o estado fundamental e as constantes de acoplamento magnético.<br>In this work we use first principles calculations based on density functional theory (DFT) to investigate the energy stability and the magnetic of chemical compounds. We studied the transition metal complexes with nitronyl nitroxide radical M(II)(P[htfac)2(NITpPy)2] [M = Co, Mn] and [M(NITmPy)2(DMSO)2] [M = Cu, Ni, Co], as well as the copper silicate Na2Cu5(Si2O7)2. By calculating the total energy, we determine the equilibrium configuration for the five metal complexes and the values of coupling constants. Moreover, we obtained their magnetization density distributions, fundamental for understanding the mechanisms of magnetic coupling in this type of system. For the copper silicate, whose magnetic properties are responsible for alternate chains of dimers and trimers, we calculate the total energy of the 32 possible configurations and determine the ground state and magnetic coupling constants.
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Almeida, Priscila Todero de 1988. "Estudo do tunelamento da magnetização em magnetos moleculares de Mn 12 via q-histerons." [s.n.], 2013. http://repositorio.unicamp.br/jspui/handle/REPOSIP/278165.
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Previous issue date: 2013<br>Resumo: O principal objetivo desse trabalho consiste em uma nova abordagem para o tunelamento da magnetização do magneto molecular Mn12, embasado em uma ampliação do modelo de Preisach. Introduziremos novos operadores que levam em conta a possibilidade de efeitos quânticos. Implementamos esse novo modelo num programa de simulação que é capaz de simular curvas de histerese e curvas de relaxação magnética sem recorrer a resolução de hamiltonianas de spin. Além disso, este programa utiliza simulação estocástica, apresentando os resultados em poucos minutos. Os resultados obtidos concordam com os experimentos realizados de histerese e relaxação magnética. Apesar de ser um modelo de simulação simples, reproduz adequadamente a fenomenologia, pois introduz os dois ingredientes essenciais de um sistema com inversão da magnetização por efeito túnel termicamente ativado: a ativação térmica, descrita pela ocupação de níveis segundo a distribuição de Boltzmann e a possibilidade do efeito túnel descrita pelo modelo de Landau¿Zenner. A consistência física do modelo é estudada através da variação de parâmetros do modelo de forma sistemática<br>Abstract: The main objective of this work consists of a new approach concerning the tunneling of the magnetization of the molecular magnet Mn12, based on an extension of the Preisach model. We will introduce new operators that take into account the possibility of quantum effects. Thus, we have implemented this new model in a simulation software that is capable of simulating hysteresis curves and magnetic relaxation curves without utilizing resolution of spin Hamiltonians. Also, this program uses stochastic simulation, presenting the results in only a few minutes. The results obtained agree with the hysteresis and relaxation experiments. Despite being a simple simulation model, it adequately reproduces the phenomenology, because it introduces two key ingredients of a system with inversion of magnetization by thermally activated tunnel effect: the thermal activation, described by the occupation of levels according to the Boltzmann distribution and the possibility of tunnel effect described by the Landau-Zenner model. The physical consistency of the model is studied by systematically varying the model¿s parameters<br>Mestrado<br>Física<br>Mestra em Física
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Pires, Heber Silas. "Síntese e caracterização de precursores e magnetos moleculares contendo ligantes do tipo oxamato." Universidade Federal de Juiz de Fora (UFJF), 2008. https://repositorio.ufjf.br/jspui/handle/ufjf/5547.
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Previous issue date: 2008-01-14<br>CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior<br>Este trabalho descreve a síntese e caracterização de três ligantes, N-(2-piridil)oxamato de etila (OPy), N-(3-piridil)oxamato de etila (MPy) e N-(4-piridil)oxamato de etila (PPy). Estes ligantes contêm pontes do tipo oxamato e encontram-se descritos na literatura; são isômeros e apresentam algumas
propriedades em comum, como por exemplo, solubilidade. A partir destes ligantes, quatro novos precursores foram sintetizados e caracterizados, três deles contendo cátions tetrametilamônio, [Me4N]2[Cu(OPy)2].9H2O (MeCuOPy), [Me4N]2[Cu(MPy)2].2H2O (MeCuMPy) e [Me4N]2[Cu(PPy)2].4H2O (MeCuPPy), e um contendo o cátion sódio em sua composição, Na2[Cu(MPy)2].4H2O (NaCuMPy).
Usando estes precursores, três cadeias inéditas foram obtidas, sendo elas CoCu(OPy)2.4H2O (CoCuOPy), CoCu(MPy)2.6H2O (CoCuMPy) e CoCu(PPy)2.7H2O (CoCuPPy). As cadeias são insolúveis na maioria dos solventes orgânicos e inorgânicos, decompondo-se em soluções ácidas. As propriedades magnéticas também foram investigadas sendo que os resultados indicaram que as cadeias
comportam-se como sistemas magnéticos unidimensionais. Todos os compostos obtidos neste trabalho foram caracterizados por análise elementar, espectroscopia vibracional na região do IV e solubilidade. Os ligantes também foram caracterizados por ponto de fusão e ressonância magnética nuclear para carbono (RMN-13C) e hidrogênio (RMN-1H). Para os precursores, foi também utilizada espectroscopia de absorção na região do ultravioleta e visível. Para a determinação do número de moléculas de solvente, no caso dos precursores e das cadeias, foi utilizada análise térmica.<br>This work describes the synthesis and characterization of three ligands, ethyl N-(2-pyridyl)oxamate (OPy), ethyl N-(3-pyridyl)oxamate (MPy) and ethyl N-(4-pyridyl)oxamate (PPy). These ligands have oxamato bridges and are described in the literature; they are isomers and present some properties in common, for example, solubility. From these ligands, four novel precursors have been synthesized and characterized, three of them containing tetramethylamonium cations (Me4N+), [Me4N]2[Cu(OPy)2].9H2O (MeCuOPy), [Me4N]2[Cu(MPy)2].2H2O (MeCuMPy) and [Me4N]2[Cu(PPy)2].4H2O (MeCuPPy), and one containing the Na+ cation in its composition, Na2[Cu(MPy)2].4H2O (NaCuMPy). Using these precursors, three new chains have been obtained, CoCu(OPy)2.4H2O (CoCuOPy), CoCu(MPy)2.6H2O (CoCuMPy) and
CoCu(PPy)2.7H2O (CoCuPPy). The chains are insoluble in most organic and inorganic solvents, decomposing in diluted acid solutions. The magnetic properties have been also investigated. The results indicated that the chains behave as onedimensional magnetic molecular systems. All compounds obtained in this work were characterized by elemental analysis, vibrational spectroscopy (IR) and solubility. The ligands were characterized also by melting point and nuclear magnetic resonance for carbon (NMR-13C) and hydrogen (NMR-1H). For the precursors, UV-Vis spectroscopy was used. To determine the number of solvent molecules in precursors and chains, thermal analysis has been used.
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Simoes, Tatiana Renata Gomes. "Síntese de magnetos moleculares à base de ligantes derivados de fenilenobis(oxamato) via estratégia metalosupramolecular." Universidade Federal de Minas Gerais, 2014. http://hdl.handle.net/1843/SFSA-9KDQ78.
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In this work, low and high dimensional molecular magnets were synthesized and characterized and their magnetic properties were investigated. Initially, reactions involving the precursor bis(2-pyridylcarbonyl) amidete of copper (II) [Cu(bpca)(H2O)2]+,
and its influence on species containing the ortho-phenylenebis(oxamate) group (opba) were investigated. Four compounds were obtained and characterized, being the X-ray structure of two of them determinated for the first time [Cu(bpca)(CF3SO3)(H2O)]·H2O and the chain {[Cu(bpca)(EtHopba)]}n . The magnetic study of {[Cu(bpca)]2[Cu(opba)(H2O)]}, [Cu2(bpca)2(H2opba)]2·3H2O and
{[Cu(bpca)(EtHopba)]}n showed antiferromagnetic coupling between the paramagnetic centers with J = -65.8, -2.36 and -0.17 cm-1, respectively. Afterwards, it was prepared a new spin-canted heterobimetallic 2-D network of formula (Bu4N)[Mn2{Cu(opba)}2ox], representing a unique example of a layered system containing copper(II) and
manganese(II) ions bridged by oxamate and oxalate groups. The intralayer antiferromagnetic interactions in the complex spin topology were evaluated through the analysis of the magnetic susceptibility data by the use of the QMC methodology which best-fit data was JCuMn = 32.5(3) cm1, e JMnMn = 2.7(3) cm1. On the third part
of this work three novel dinuclear compounds with the chemical formula
[Cu(opba)Cu(phen)(dmso)2].2H2O, [Cu(opba)Cu(dap)(H2O)].H2O and
[Cu(opba)Cu(dap-OH)(H2O)].2H2O with phen = 1,10 phenanthroline, dap = 1,3 diaminopropane and dap-OH = 2-hidroxi-1,3 diaminopropane have been synthesized and their crystal structures have been determined. The fiting of magnetic data revealed a strong antiferromagnetic coupling among the metal centers through
the oxamate bridge with J = -358.8, -366.0 e -392.1 cm-1 respectively. Finally, it was studied the solvent-driven preparation and structural characterization of the dinuclear compound [Cu(bipy)(H2mpba)]2·2H2O and the neutral chain [Cu(bipy)(H2mpba)]·dmso [bipy = 2,2'-bipyridine and H4mpba = N,N'-1,3-phenylenebis(oxamic acid)]. The
reversible interconversion between them is also presented and the magnetic studies reveals weak intradinuclear (J = -0.81 cm-1) and intrachain magnetic interactions (J = - 0.22 cm-1).<br>Neste trabalho foram realizadas sínteses, caracterizações e estudos das propriedades magnéticas de magnetos moleculares de baixa e alta dimensionalidades. Primeiramente foram investigadas reações envolvendo o precursor bis(2-piridilcarbonil)amideto de cobre(II), [Cu(bpca)(H2O)2]+ e sua influência em espécies contendo o grupo orto-fenilenobis(oxamato) (opba). Quatro compostos foram obtidos e caracterizados, dentre eles dois cujas estruturas cristalinas são inéditas: [Cu(bpca)(CF3SO3)(H2O)]·H2O e a cadeia {[Cu(bpca)(EtHopba)]}n . O estudo magnético de {[Cu(bpca)]2[Cu(opba)(H2O)]}, [Cu2(bpca)2(H2opba)]2·3H2O e {[Cu(bpca)(EtHopba)]}n mostraram acoplamento antiferromagnético entre os centros paramagnéticos, com parâmetros J = -65,8, -2,36 e -0,17 cm-1, respectivamente. Posteriormente foi preparada a rede bidimensional heterometálica de fórmula (Bu4N)[Mn2{Cu(opba)}2ox], que representa o único exemplo de plano contendo íons de CuII, MnII conectados por grupos oxamato e oxalato. As interações antiferromagnéticas dos spins dentro das camadas foram analisadas através dos dados de suscetibilidade magnética, sendo caracterizado o spin-canting. O uso da metodologia QMC permitiu determinar os valores dos acoplamentos JCuMn = -32,5(3) cm-1, e JMnMn = -2,7(3) cm-1. Na terceira parte deste trabalho, foram sintetizados e caracterizados estruturalmente três novos compostos dinucleares: [Cu(opba)Cu(phen)(dmso)2]·2H2O, [Cu(opba)Cu(dap)(H2O)]·H2O e [Cu(opba)Cu(dap-OH)(H2O)]·2H2O; phen = 1,10-fenantrolina, dap = 1,3-diaminopropano e dapOH = 2-hidroxi-1,3-diaminopropano. O tratamento dos dados magnéticos mostrou forte acoplamento antiferromagnético intramolecular, com valores de J =-358,8, -366,0 e - 392,1 cm-1, respectivamente. Finalmente, estudou-se a síntese controlada pelos solventes do meio reacional para a preparação e caracterização estrutural de um composto dinuclear Cu(bipy)(H2mpba)]2·2H2O, e de uma cadeia neutra [Cu(bipy)(H2mpba)]·dmso [bipy = 2,2'-bipiridina, H4mpba = ácido N,N'-1,3- fenilenobis(oxâmico)]. Também é mostrada a interconversão reversível entre eles. O estudo magnético mostrou fracas interações magnéticas intradinuclear (J = -0,81 cm-1) e intracadeia (J = -0,22 cm-1).
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Rodrigues, Aline do Nascimento. "Estudo de sistemas magnéticos modeláveis mediante sub-redes." Universidade Federal de Sergipe, 2014. https://ri.ufs.br/handle/riufs/5362.
Full textAbstract:
We have modeled some magnetic systems, which consists of a number
of sublattices, in the mean field approximation. This is possible in crystalline
systems formed by two or more magnetic ions coupled by specific interactions
such as the crystal field, exchange, among others. The main idea is to solve the
microscopic Hamiltonian that models a given magnetic system in order to obtain
their magnetic equation of state: M (H, T). For this, we use the appropriate
arrangements to different magnetic (ferro-, ferri- and antiferro- magnetic)
scheme sublattices. From the solutions of the Hamiltonian (eigenvalues and
eigenvectors), physical quantities of interest were determined. In principle we
consider systems with localized magnetism due to 3d and 4f electrons with the
participation of non-magnetic ligands including 3d-4f systems with the presence
of crystal field. In this dissertation we use the model of two-and three sublattices
in order to obtain the equation of state for the following systems: RKKY
exchange in RNi2B2C, superexchange in (Y3-zRz)(T1xFe1-x)(T2yFe3-y)O12, LixFe3-
xO4 and (NixMn1-x)1.5[Cr(CN)6]. In these formulas, R represents a rare earth ion,
T1 and T2 represent non-magnetic ions. Some representative cases are
presented to illustrate the different equations of state and behavior of
sublattices, metamagnetism, temperature compensation, etc. The extension to
other similar systems can be direct or need to incorporate additional
phenomenological parameters.<br>Consideramos neste estudo sistemas magnéticos modeláveis mediante
sub- redes na aproximação do campo médio. Isto é possível em sistemas
cristalinos formados por dois ou mais íons magnéticos acoplados por interações
específicas como as do campo cristalino, troca, entre outros. A ideia central é
resolver o hamiltoniano microscópico que modela um determinado sistema
magnético de maneira a se obter sua equação de estado magnética: M(H,T).
Para isto usamos o esquema de sub- redes adequado a diferentes arranjos
magnéticos (ferro-, ferri- e antiferro- magnéticos). Com as soluções do
hamiltoniano (autovalores e autovetores), grandezas físicas de interesse foram
determinadas. Em princípio, consideramos sistemas com magnetismo
localizado devido a elétrons 3d e 4f com participação de ligandos não
magnéticos incluindo sistemas 3d-4f com presença de campo cristalino. Neste
trabalho de dissertação empregamos o modelo de duas e três sub- redes para
obter as equações de estado nos seguintes sistemas: troca tipo RKKY em
RNi2B2C, supertroca em (Y3-zRz)(T1xFe1-x)(T2yFe3-y)O12, LixFe3-xO4 e (NixMn1-
x)1.5[Cr(CN)6]. Nestas fórmulas, R representa um íon de terra rara, T1 e T2
representam íons não magnéticos. Alguns casos representativos são
apresentados para exemplificar as diferentes equações de estado e
comportamento das sub- redes, metamagnetismo, temperatura de
compensação etc. Em princípio, a extensão para outros sistemas semelhantes,
usando os modelos apresentados aqui, pode ser direta ou precisar incorporar
parâmetros fenomenológicos adicionais.
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Krupskaya, Yulia. "Magnetic Properties of Molecular and Nanoscale Magnets." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2011. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-73289.
Full textAbstract:
The idea of miniaturizing devices down to the nanoscale where quantum ffeffects become relevant demands a detailed understanding of the interplay between classical and quantum properties. Therefore, characterization of newly produced nanoscale materials is a very important part of the research in this fifield. Studying structural and magnetic properties of nano- and molecular magnets and the interplay between these properties reveals new interesting effects and suggests ways to control and optimize the respective material. The main task of this thesis is investigating the magnetic properties of molecular magnetic clusters and magnetic nanoparticles recently synthesized by several collaborating groups. This thesis contains two main parts focusing on each of these two topics.
In the first part the fundamental studies on novel metal-organic molecular complexes is presented. Several newly synthesized magnetic complexes were investigated by means of different experimental techniques, in particular, by electron spin resonance spectroscopy. Chapter 1 in this part provides the theoretical background which is necessary for the interpretation of the effects observed in single molecular magnetic clusters. Chapter 2 introduces the experimental techniques applied in the studies. Chapter 3 contains the experimental results and their discussion. Firstly, the magnetic properties of two Ni-based complexes are presented. The complexes possess different ligand structures and arrangements of the Ni-ions in the metal cores. This difffference dramatically affffects the magnetic properties of the molecules such as the ground state and the magnetic anisotropy. Secondly, a detailed study of the Mn2Ni3 single molecular magnet is described. The complex has a bistable magnetic ground state with a high spin value of S = 7 and shows slow relaxation and quantum tunnelling of the magnetization. The third section concentrates on a Mn(III)-based single chain magnet showing ferromagnetic ordering of the Mn-spins and a strong magnetic anisotropy which leads to a hysteretic behavior of the magnetization. The last section describes a detailed study of the static and dynamic magnetic properties of three Mn-dimer molecular complexes by means of static magnetization, continuous wave and pulse electron spin resonance measurements. The results indicate a systematic dependence of the magnetic properties on the nearest ligands surrounding of the Mn ions.
The second part of the thesis addresses magnetic properties of nano-scaled magnets such as carbon nanotubes fifilled with magnetic materials and carbon-coated magnetic nanoparticles. These studies are eventually aiming at the possible application of these particles as agents for magnetic hyperthermia. In this respect, their behavior in static and alternating magnetic fifields is investigated and discussed. Moreover, two possible hyperthermia applications of the studied magnetic nanoparticles are presented, which are the combination of a hyperthermia agents with an anticancer drug and the possibility to spatially localize the hyperthermia effffect by applying specially designed static magnetic fifields.
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Henderson, John. "SPIN QUANTUM DYNAMICS IN MOLECULAR MAGNETS." Doctoral diss., University of Central Florida, 2009. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3535.
Full textAbstract:
Molecular magnets are ideal systems to probe the realm that borders quantum and classical physics, as well as to study decoherence phenomena in nanoscale systems. The control of the quantum behavior of these materials and their structural characteristics requires synthesis of new complexes with desirable properties which will allow probing of the fundamental aspects of nanoscale physics and quantum information processing. Of particular interest among the magnetic molecular materials are single-molecule magnets (SMMs) and antiferromagnetic (AFM) molecular wheels in which the spin state of the molecule is known to behave quantum mechanically at low temperatures. In previous experiments the dynamics of the magnetic moment of the molecules is governed by incoherent quantum tunneling. Short decoherence times are mainly due to interactions between molecular magnets within the crystal and interactions of the electronic spin with the nuclear spin of neighboring ions within the molecule. This decoherence problem has imposed a limit to the understanding of the molecular spin dynamics and the sources of decoherence in condensed matter systems. Particularly, intermolecular dipolar interactions within the crystal, which shorten the coherence times in concentrated samples, have stymied progress in this direction. Several recent works have reported a direct measurement of the decoherence time in molecular magnets. This has been done by eliminating the dephasing created by dipolar interactions between neighboring molecules. This has been achieved by a) a dilution of the molecules in a liquid solution to decrease the dipolar interaction by separating the molecules, and b) by polarizing the spin bath by applying a high magnetic field at low temperatures. Unfortunately, both approaches restrict the experimental studies of quantum dynamics. For example, the dilution of molecular magnets in liquid solution causes a dispersion of the molecular spin orientation and anisotropy axes, while the large fields required to polarize the spin bath overcome the anisotropy of the molecular spin. In this thesis I have explored two methods to overcome dipolar interactions in molecular magnets: a) studying the dynamics of molecular magnets in single crystals where the separation between magnetic molecules is obtained by chemical doping or where the high crystalline quality allows observations intrinsic to the quantum mechanical nature of the tunneling of the spin, and b) studying the electronic transport through an individual magnetic molecule which has been carefully placed in a single-electron transistor device. I have used EPR microstrip resonators to measure Fe17Ga molecular wheels within single crystals of Fe18 AFM wheels, as well as demonstrating, for the first time in a Single Molecule Magnet, the complete suppression of a Quantum Tunneling of the Magnetization transition forbidden by molecular symmetry.<br>Ph.D.<br>Department of Physics<br>Sciences<br>Physics PhD
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Aliabadi, Azar. "ESR and Magnetization Studies of Transition Metal Molecular Compounds." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-195440.
Full textAbstract:
Molecule-based magnets (molecular magnets) have attracted much interest in recent decades both from an experimental and from a theoretical point of view, not only because of their interesting physical effects, but also because of their potential applications: e.g., molecular spintronics, quantum computing, high density information storage, and nanomedicine. Molecular magnets are at the very bottom of the possible size of nanomagnets. On reducing the size of objects down to the nanoscale, the coexistence of classical properties and quantum properties in these systems may be observed. In additional, molecular magnets exist with structural variability and permit selective substitution of the ligands in order to alter their magnetic properties. Therefore, these characteristics make such molecules suitable candidates for studying molecular magnetism. They can be used as model systems for a detailed understanding of interplay between structural and magnetic properties of them in order to optimize desired magnetic properties.
This thesis considers the investigation of magnetic properties of several new transition metal molecular compounds via different experimental techniques (continuous wave electron spin resonance (CW ESR), pulse ESR, high-field/high-frequency ESR (HF-ESR) and static magnetization techniques).
The first studied compounds were mono- and trinuclear Cu(II)-(oxamato, oxamidato)/bis(oxamidato) type compounds. First, all components of the g-tensor and the tensors of onsite ACu and transferred AN HF interactions of mononuclear Cu(II)- bis(oxamidato) compounds have been determined from CW ESR measurements at 10 GHz and at room temperature and pulse ELDOR detected NMR measurements at 35 GHz and at 20 K. The spin density distributions of the mononuclear compounds have been calculated from the experimentally obtained HF tensors. The magnetic exchange constants J of their corresponding trinuclear compounds were determined from susceptibility measurements versus temperature. Our discussion of the spin density distribution of the mononuclear compounds together with the results of the magnetic characterization of their corresponding trinuclear compounds show that the spin population of the mononuclear compounds is in interplay with the J values of their corresponding trinuclear compounds.
The second studied compounds were polynuclear Cu(II)-(bis)oxamato compounds with ferrocene and ferrocenium ligands. The magnetic properties of these compounds were studied by susceptibility measurements versus temperature to determine J values. In addition, the ESR technique is used to investigate the magnetic properties of the studied compounds because they contain two different magnetic ions and because only the ESR technique can selectively excite different electron spin species. These studies together with geometries of the ferrocenium ligands determined by crystallographic studies indicate that the magnetic interaction between a central Cu(II) and a Fe(III) ions changed from the antiferromagnetic coupling to the ferromagnetic coupling when a stronger distortion of the axial symmetry in the feroccenium cation exists. Therefore, the degree of the distortion of the feroccenium cation is a control parameter for the sign of the interaction between the central Cu(II) ion and the Fe(III) spins of the studied compounds.
The last two studied molecular magnets were a binuclear Ni(II) compound (Ni(II)-dimer) and a cube-like tetranuclear compound with a [Fe4O4]-cube core (Fe4-cube). HF-ESR measurements enabled us to determine the g-factor, the sign, and the absolute value of the magnetic anisotropy parameters. Using this information together with static magnetization measurements, the J value and the magnetic ground state of the studied compounds have been determined. In Ni(II)-dimer, two Ni(II) ions, each having a spin S = 1, are coupled antiferromagnetically that leads to a ground state with total spin Stot = 0. An easy plane magnetic anisotropy with a preferable direction for each Ni(II) ion is found. For Fe4-cube, a ground state with total spin Stot = 8 has been determined. The analysis of the frequency dependence and temperature dependence of HF-ESR lines reveals an easy axis magnetic anisotropy (Dcube = -22 GHz (-1 K)) corresponding to an energy barrier of U = 64 K for the thermal relaxation of the magnetization. These results indicate that Fe4-cube is favorable to show single molecular magnet (SMM) behavior.
Books on the topic "Magnetos moleculares"
1
Roberta, Sessoli, and Villain Jacques, eds. Molecular nanomagnets. Oxford University Press, 2006.
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Bartolomé, Juan, Fernando Luis, and Julio F. Fernández, eds. Molecular Magnets. Springer Berlin Heidelberg, 2014. http://dx.doi.org/10.1007/978-3-642-40609-6.
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Linert, Wolfgang, and Michel Verdaguer, eds. Molecular Magnets Recent Highlights. Springer Vienna, 2003. http://dx.doi.org/10.1007/978-3-7091-6018-3.
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NATO Advanced Research Workshop on Magnetic Molecular Materials (1990 Il Ciocco, Italy). Magnetic molecular materials. Kluwer Academic Publishers, 1991.
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Sieklucka, Barbara, and Dawid Pinkowicz, eds. Molecular Magnetic Materials. Wiley-VCH Verlag GmbH & Co. KGaA, 2017. http://dx.doi.org/10.1002/9783527694228.
Full textBook chapters on the topic "Magnetos moleculares"
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Taran, Gheorghe, Edgar Bonet, and Wolfgang Wernsdorfer. "Molecular Magnetism." In Handbook of Magnetism and Magnetic Materials. Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-63101-7_18-1.
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Sarachik, Myriam P. "Magnetic Avalanches in Molecular Magnets." In NanoScience and Technology. Springer Berlin Heidelberg, 2014. http://dx.doi.org/10.1007/978-3-642-40609-6_5.
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Gatteschi, D. "Magnetic Resonances and Spin Dynamics in Molecular Magnets." In Molecular Magnetism: From Molecular Assemblies to the Devices. Springer Netherlands, 1996. http://dx.doi.org/10.1007/978-94-017-2319-0_6.
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Schnack, Jürgen. "Molecular magnetism." In Quantum Magnetism. Springer Berlin Heidelberg, 2004. http://dx.doi.org/10.1007/bfb0119593.
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Caneschi, Andrea, Dante Gatteschi, and Roberta Sessoli. "Structural Magnetic Correlations in Phase Transitions of Molecular Magnets." In Magnetic Molecular Materials. Springer Netherlands, 1991. http://dx.doi.org/10.1007/978-94-011-3254-1_15.
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Shatruk, Michael, Silvia Gómez-Coca, and Kim R. Dunbar. "Molecular Magnetism." In Molecular Magnetic Materials. Wiley-VCH Verlag GmbH & Co. KGaA, 2016. http://dx.doi.org/10.1002/9783527694228.ch2.
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Aromí, Guillem, Patrick Gamez, and Olivier Roubeau. "Molecular Magnetism." In Spin States in Biochemistry and Inorganic Chemistry. John Wiley & Sons, Ltd, 2015. http://dx.doi.org/10.1002/9781118898277.ch12.
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Mathonière, Corine, Hiroko Tokoro, and Shin-ichi Ohkoshi. "Molecular Photomagnets." In Molecular Magnetic Materials. Wiley-VCH Verlag GmbH & Co. KGaA, 2016. http://dx.doi.org/10.1002/9783527694228.ch13.
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Palstra, Thomas T. M., and Alexey O. Polyakov. "Molecular Multiferroics." In Molecular Magnetic Materials. Wiley-VCH Verlag GmbH & Co. KGaA, 2016. http://dx.doi.org/10.1002/9783527694228.ch16.
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Zhang, Wei-Xiong, Ming-Hua Zeng, and Xiao-Ming Chen. "Porous Molecular Magnets." In Molecular Magnetic Materials. Wiley-VCH Verlag GmbH & Co. KGaA, 2016. http://dx.doi.org/10.1002/9783527694228.ch10.
Full textConference papers on the topic "Magnetos moleculares"
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Sugano, T., F. L. Pratt, M. Kurmoo, et al. "Magnetic ordering in some organic molecular magnets." In International Conference on Science and Technology of Synthetic Metals. IEEE, 1994. http://dx.doi.org/10.1109/stsm.1994.835704.
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Tagaya, Yoichi, Yasunaga Mitsuya, Susumu Ogata, Hedong Zhang, and Kenji Fukuzawa. "A Simulation Method for Spreading Dynamics of Molecularly Thin Lubricant Films on Magnetic Disks Using Bead-Spring Model." In World Tribology Congress III. ASMEDC, 2005. http://dx.doi.org/10.1115/wtc2005-64393.
Full textAbstract:
An effective simulation technique for describing the spreading properties of molecularly thin lubricant films on magnetic disks has been developed. We propose a molecular precipitation method that can simulate initial molecule arrangement of the films dip-coated onto the disks. Reptation and Rouse models as the model of the molecular motion, and molecular insertion and molecular precipitation methods as the method for putting molecules in initial positions were compared. From the results of the spreading profiles and diffusion coefficients, it has been revealed that the molecular precipitation method combined with the Rouse model is effective in simulating the spreading of the lubricant films.
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Xuan, Yimin, Qiang Li, and Bing Li. "Numerical Simulation Method of Microstructure and Optical Characteristics of Magnetic Fluids." In 2007 First International Conference on Integration and Commercialization of Micro and Nanosystems. ASMEDC, 2007. http://dx.doi.org/10.1115/mnc2007-21412.
Full textAbstract:
A magnetic fluid possesses a variety of unique characteristics because of both the magnetism of nanoparticles material and the fluidity of the carrier liquid. The characteristics of magnetic fluid depend upon the microstructure of the magnetic nanoparticles aggregation. This paper aims to use the molecular dynamic method to simulate the microstructure formation in a magnetic fluid. A number of inner and external potentials and forces acting on the magnetic fluid are included to reveal the effects of these potentials and forces to the magnetic fluid morphology. Further, a numerical method to study the optical feature of the magnetic fluid films is developed with the Monte Carlo method based on the simulated microstructures, which tracks the spread process of ray transmitting through the magnetic fluid film and computes the spectral transmittivity of the magnetic film. Some factors of affecting the spectral transmittivity of magnetic fluid film are investigated, such as the film thickness, the concentration and diameter of magnetic nanoparticles, and strength of externally applied magnetic field. By combining the molecular dynamic simulation and the ray-tracing method, this paper provides a useful tool for investigating the morphology and optical characteristic of a ferrofluid film.
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Gangopadhyay, Palash, Guy Koeckelberghs, and André Persoons. "Molecular magneto-optics." In SPIE Organic Photonics + Electronics, edited by Jean-Michel Nunzi. SPIE, 2014. http://dx.doi.org/10.1117/12.2061841.
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Satoh, Akira. "Dependence of the Regime of Aggregate Structures of Magnetic Rod-Like Particles on the Magnetic Model." In ASME 2016 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/imece2016-65352.
Full textAbstract:
In the present study, we attempt to discuss the dependence of the regime of the aggregate structures of magnetic rod-like particles on the magnetic model. Moreover, we briefly discuss the characteristic magneto-rheological properties of each magnetic model. Three representative magnetic models are here addressed for a magnetic rod-like particle, that is, (a) a spherocylinder particle with a dipole moment at the particle center (dipole model), (b) a spherocylinder particle with a plus and a minus charge at the center of each hemi-sphere (charge model) and (c) a spherocylinder with a dipole moment in a direction normal to the particle axis direction at the particle center (hematite model). For each magnetic model, molecular simulations based on the Monte Carlo method have been performed in order to elucidate the influences of magnetic particle-particle and particle-field interactions on the aggregate structures of magnetic spherocylinder particles in thermodynamic equilibrium. For the case of the dipole model, long stable raft-like clusters are gradually formed with increasing magnetic particle-particle interaction strength, and these raft-like clusters dissociate into the formation of chain-like clusters with increasing magnetic field strength. For the case of the charge model, long and thick chain-like clusters are more significantly formed with increasing magnetic interactions, and the thick chain-like clusters in the field direction become further thicker with increasing magnetic field strength. For the hematite model, long raft-like clusters are formed and these clusters still remain and incline in the field direction in a strong magnetic field situation. From these results, it is evident that the different magnetic model gives rise to the significantly different regime of the aggregate structures. Moreover, Brownian dynamics simulations have been conduced in order to clarify the dependence of the magneto-rheological characteristics on the regime of the above-mentioned particle aggregates. Among these magnetic models, the charge model yields the largest magneto-rheological effect, whereas the hematite model provides the negative viscosity due to the magnetic properties of particles.
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Tsumori, Fujio, Kenji Hatama, Hyungoo Kang, Toshiko Osada, and Hideshi Miura. "Magneto-FEM analysis for micro actuator using array of magnetic elements." In 2013 8th IEEE International Conference on Nano/Micro Engineered and Molecular Systems (NEMS). IEEE, 2013. http://dx.doi.org/10.1109/nems.2013.6559857.
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Gruselle, Michel, Bernard Malézieux, Cyrille Train, et al. "Optically active molecular magnets." In SPIE Proceedings, edited by Arnold Rosental. SPIE, 2005. http://dx.doi.org/10.1117/12.639178.
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Barker, Alex J., Brant Cage, Stephen Russek, Ruchira Garg, Robin Shandas, and Conrad R. Stoldt. "Tailored Nanoscale Contrast Agents for Magnetic Resonance Imaging." In ASME 2005 International Mechanical Engineering Congress and Exposition. ASMEDC, 2005. http://dx.doi.org/10.1115/imece2005-81503.
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Two potential molecular imaging vectors are investigated for material properties and magnetic resonance imaging (MRI) contrast improvement. Monodisperse magnetite (Fe3O4) nanocrystals ranging in size from 7 to 22 nm are solvothermally synthesized by thermolysis of Fe(III) acetylacetonate (Fe(AcAc)3) both with and without the use of heptanoic acid (HA) as a capping ligand. For the resulting Fe3O4 nanocrystals, X-Ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), and superconducting quantum interference device magnetometry (SQUID) is used to identify the average particle size, monodispersity, crystal symmetry, and magnetic properties of the ensembles as a function of time. The characterization study indicates that the HA synthesis route at 3 hours produced nanoparticles with the greatest magnetic anisotropy (15.8 × 104 J/m3). The feasibility of Fe8 single molecule magnets (SMMs) as a potential MRI contrast agent is also examined. SQUID magnetization measurements are used to determine anisotropy and saturation of the potential agents. The effectiveness of the Fe3O4 nanocrystals and Fe8 as potential MRI molecular probes is evaluated by MRI contrast improvement using 1.5 mL phantoms dispersed in de-ionized water. Results indicate that the magnetically optimized Fe3O4 nanocrystals and Fe8 SMMs hold promise for use as contrast agents based on the reported MRI images and solution phase T1/T2 shortening.
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ANDRES, H. P., S. DECURTINS, and H. U. GÜDEL. "NEUTRON SCATTERING OF MOLECULAR MAGNETS." In Proceedings of the Seventh Summer School on Neutron Scattering. WORLD SCIENTIFIC, 1999. http://dx.doi.org/10.1142/9789814503976_0008.
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Kuroda, Takayoshi. "MOLECULAR MAGNETS FOR QUANTUM COMPUTATION." In Molecular Realizations of Quantum Computing 2007. WORLD SCIENTIFIC, 2009. http://dx.doi.org/10.1142/9789812838681_0006.
Full textReports on the topic "Magnetos moleculares"
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Topping, Craig V. Molecular Magnets and Reduced Dimensionality. Office of Scientific and Technical Information (OSTI), 2012. http://dx.doi.org/10.2172/1058056.
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Rothberg, G. M. Magnetism and molecular interactions at solid surfaces. Office of Scientific and Technical Information (OSTI), 1991. http://dx.doi.org/10.2172/6229364.
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Jarvie, T. P. Molecular structure and motion in zero field magnetic resonance. Office of Scientific and Technical Information (OSTI), 1989. http://dx.doi.org/10.2172/7040223.
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Liu, Amy Y., Tunna Baruah, and Kyungwha Park. Prediction of Magnetic and Electronic Phenomena in Molecular-Assembled Crystals. Defense Technical Information Center, 2008. http://dx.doi.org/10.21236/ada491900.
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O'Hara, D. J. Molecular Beam Epitaxy and High-Pressure Studies of van der Waals Magnets. Office of Scientific and Technical Information (OSTI), 2019. http://dx.doi.org/10.2172/1562380.
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Samarth, Nitin. Acquisition of Molecular Beam Epitaxy System for Fabrication of Hybrid Magnetic/Semiconductor Heterostructures. Defense Technical Information Center, 2000. http://dx.doi.org/10.21236/ada384761.
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Rucker, S. P. Two-dimensional nuclear magnetic resonance studies of molecular structure in liquids and liquid crystals. Office of Scientific and Technical Information (OSTI), 1991. http://dx.doi.org/10.2172/5096566.
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Dunbar, Kim. Molecular Magnets Based on a Modular Approach: Investigation of Coupling, Anisotropy and Electronic Factors on Bistability. Office of Scientific and Technical Information (OSTI), 2019. http://dx.doi.org/10.2172/1494810.
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Tranchida, Julien Guy, Mitchell Wood, and Stan Gerald Moore. Coupled Magnetic Spin Dynamics and Molecular Dynamics in a Massively Parallel Framework: LDRD Final Report. Office of Scientific and Technical Information (OSTI), 2018. http://dx.doi.org/10.2172/1493836.
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Geiger, David K. Molecular Structure Laboratory. Fourier Transform Nuclear Magnetic Resonance (FTNMR) Spectrometer and Ancillary Instrumentation at SUNY Geneseo. Office of Scientific and Technical Information (OSTI), 2015. http://dx.doi.org/10.2172/1235371.
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