Nuclear Magnetic Resonance in Ferromagnets and Antiferromagnets

Петров, М. П.; Turov, E. A.

doi:10.1080/05704927208081702

Cited by 11 publications

(9 citation statements)

References 82 publications

(50 reference statements)

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“…The upper signs correspond to such parameter values of the coupled system at which Iwsl > Iw y I (w+-mode is s-like in this parameter range, it is suppressed as a result of coupling, co_-mode is elike, it is enhanced). It should be noted that the terms "s-and e-like modes" are accepted analogously to nuclear-like and electron-like modes of coupled oscillations of nuclear and electron magnetizations in magnets [10]. Lower signs correspond to the situation Iw 5 1 < Iwyl -the inverse effect takes place here.…”

Section: Esr Spectrum Of a Coupled System Of Localized And Delocalizementioning

confidence: 99%

Coupled (localized+delocalized) electron spins dynamics in polymer phase of RbC60 fulleride

Fokina

Khutsishvili

1999

Appl. Magn. Reson.

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The transverse response (transverse dynamic susceptibility) of coupled localized (s) and delocalized (e) electron spins of a metal paramagnet as well as the longitudinal dynamic response of such a system (to be registered by a longitudinal coil) to the modulation of microwave power saturating electron spin resonance (ESR) are calculated. The ESR spectrum is analytically decomposed into two Lorentzians with normal resonance frequencies and decay rates of the coupled localized +delocalized electron spin system. In the case of relaxationally coupled s-and e-spins the longitudinal response is decomposed into two "relaxational" Lorentzians squared with amplitudes containing ESR lineshapes with above-mentioned shifted frequencies and linewidths as well as enhancement-suppression coefficients of magnetization evolution. These results are essential for the interpretation of experiments on longitudinal response in metal paramagnets, the latter being the source of important information on longitudinal electron relaxation; in particular, for extraction of information from longitudinal response experiments in the polymer phase of RbC 60 fulleride, where the obtained results describe the observed form of the ESR spectrum and the main features of the longitudinal response.

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Section: Esr Spectrum Of a Coupled System Of Localized And Delocalizementioning

confidence: 99%

Coupled (localized+delocalized) electron spins dynamics in polymer phase of RbC60 fulleride

Fokina

Khutsishvili

1999

Appl. Magn. Reson.

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“…At present it is well established that in the magnetic materials there are thermal fluctuations of the direction of electronic magnetization M ! e [1,[4][5][6]. These thermal fluctuations in the direction of M !…”

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confidence: 96%

“…e does not depend on time. Within the framework of this model nuclear spin-spin interactions give the contribution only to the transverse (spin-spin) relaxation rate (T 2 j1 ) [1]. On the other hand, from NMR experiments, executed on the YIG films with the different concentration of magnetic nuclei 57 Fe, it follows that the longitudinal relaxation rate (T 1 j1 ) depends on the concentration of magnetic nuclei [2].…”

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confidence: 99%

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Spin–Spin Interactions and Nuclear Magnetic Relaxation in Magnetic Solids

Sergeev

Polulyakh

2006

Hyperfine Interact

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The influence of the orientational fluctuations of the electronic magnetization, which modulate nuclear spin-spin interactions (Suhl-Nakamura and dipole-dipole), on the spin-lattice relaxation of magnetic nuclei with spin I = 1/2 in the magnetically ordered solids has been investigated. It has been shown that this mechanism of the spin-lattice relaxation is less effective in comparison with the process of spin-lattice relaxation caused by the direct fluctuations of hyperfine fields, which appear when there are the fluctuations of electronic magnetization direction.At present for analysis of the influence of nuclear spin-spin (Suhl-Nakamura and dipole-dipole [1]) interactions on the nuclear spin-relaxation of magnetic nuclei in the magnetic materials is used, mainly, the model, which can be named as the model of Frigid_ lattice [1]. In this model it is assumed that the direction of the electron magnetization M ! e does not depend on time. Within the framework of this model nuclear spin-spin interactions give the contribution only to the transverse (spin-spin) relaxation rate (T 2 j1 ) [1]. On the other hand, from NMR experiments, executed on the YIG films with the different concentration of magnetic nuclei 57 Fe, it follows that the longitudinal relaxation rate (T 1 j1 ) depends on the concentration of magnetic nuclei [2]. The influence of nuclear dipole-dipole interactions on the longitudinal relaxation rate is well known for the diamagnetic materials and this phenomenon is caused by thermal fluctuation of nuclear interactions [3]. At present it is well established that in the magnetic materials there are thermal fluctuations of the direction of electronic magnetization M ! e [1, 4-6]. These thermal fluctuations in the direction of M ! e induce the thermal fluctuations of nuclear spin-spin interactions and this can lead to the fact that the nuclear spin-spin interactions can give the contribution to the longitudinal relaxation rate (T 1 j1 ).

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“…Pode-se também mostrar que o acoplamento dos dois sistemas ressonantes leva a um aumento, ou amplificação, do campo de rf aplicado 39 .…”

Section: Ressonância Em Um Sistema De Dois Spins Acopladosunclassified

Estudo do composto intermetálico GdAl2 via ressonância magnética nuclear em campo magnético externo nulo

Oliveira‐Silva¹

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AGRADECIMENTOSAgradeço ao meu orientador, Prof. Dr. Tito José Bonagamba, pela paciência, dedicação e pela sabedoria que me foram passadas durante este trabalho e por acreditar na capacidade humana e dar oportunidades a todos de mostrarem o seu valor.Ao meu ex-orientador Prof. Dr. Alvicler Magalhães por ter me ajudado no início da minha carreira científica.Ao parceiro de trabalho e amigo Dr. José Roberto Tozoni, sempre presente neste projeto, pronto para ajudar e discutir os resultados.Ao Prof. Dr. Jair Carlos Checon de Freitas, como o nosso maior motivador para começar a fazer pesquisa na área de RMN em campo zero.Ao Dr. Rubén Auccaise Estrada, que muito contribuiu para a consolidação desta nova área de pesquisa, no Grupo de Ressonância Magnética do Instituto de Física de São Carlos, pela ajuda na correção deste trabalho e pela amizade.Ao Daniel César Braz, que recentemente ingressou no nosso grupo, primeiramente pela amizade e também pela valiosa contribuição para a análise dos dados obtidos.Ao Prof. Dr. Alberto Passos Guimarães, pelas discussões, correções e incentivo.Ao Prof. Dr. Jair Carlos Checon de Freitas, como maior motivador para começar a fazer pesquisa na área de RMN em campo zero Aos meus amigos Éverton Sérgio Stracanholli e Marco Aurélio Ubirajara, desde nossas graduações sempre presentes para conversar e me apoiar.Aos meus pais Antonio e Maria Madalena de Oliveira Silva desde cedo educando e incentivando os estudos, graças a eles este trabalho se finalizou. Gd and 157 Gd (both spin 3/2). In this case that, also it was measured the quadrupole couplings values directly from spectra, but could not measure them from the quadrupole oscillations. Varying the temperature, it was also observed that the behavior of the magnetization follows the law of Curie-Weiss, through the displacement of the observed lines.

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Nuclear Magnetic Resonance in Ferromagnets and Antiferromagnets

Cited by 11 publications

References 82 publications

Coupled (localized+delocalized) electron spins dynamics in polymer phase of RbC60 fulleride

Coupled (localized+delocalized) electron spins dynamics in polymer phase of RbC60 fulleride

Spin–Spin Interactions and Nuclear Magnetic Relaxation in Magnetic Solids

Estudo do composto intermetálico GdAl2 via ressonância magnética nuclear em campo magnético externo nulo

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