Spin fluctuations in isotropic ferromagnets near TC

P. Böni

doi:10.1016/0921-4526(93)90111-I

Spin fluctuations in isotropic ferromagnets near T_C

P. Böni

Paul Scherrer Institute

Research output: Contribution to journal › Article › peer-review

5 Scopus citations

Abstract

By means of polarized neutrons it is possible to measure different magnetic spin excitation modes in isotropic ferromagnets. The data from EuS shows that the demagnetizing fields have a profound effect on the spin excitations below and above T_C. In particular they prevent the long-wavelength spin fluctuations δS {norm of matrix} q from diverging at T_C. This behaviour is reflected in the dynamics of the paramagnetic fluctuations and the spin waves below T_C. The modes with longitudinal polarization are more damped than their transverse counterparts. Above T_C the relaxation rates follow rather precisely the dipolar dynamic scaling functions calculated recently by mode-coupling theory. Below T_C, the parallel magnetization fluctuations, δS {norm of matrix} M, are significantly stronger in EuS than in Ni.

Original language	English
Pages (from-to)	94-102
Number of pages	9
Journal	Physica B: Condensed Matter
Volume	192
Issue number	1-2
DOIs	https://doi.org/10.1016/0921-4526(93)90111-I
State	Published - Oct 1993
Externally published	Yes

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title = "Spin fluctuations in isotropic ferromagnets near TC",

abstract = "By means of polarized neutrons it is possible to measure different magnetic spin excitation modes in isotropic ferromagnets. The data from EuS shows that the demagnetizing fields have a profound effect on the spin excitations below and above TC. In particular they prevent the long-wavelength spin fluctuations δS {norm of matrix} q from diverging at TC. This behaviour is reflected in the dynamics of the paramagnetic fluctuations and the spin waves below TC. The modes with longitudinal polarization are more damped than their transverse counterparts. Above TC the relaxation rates follow rather precisely the dipolar dynamic scaling functions calculated recently by mode-coupling theory. Below TC, the parallel magnetization fluctuations, δS {norm of matrix} M, are significantly stronger in EuS than in Ni.",

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AU - Böni, P.

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N2 - By means of polarized neutrons it is possible to measure different magnetic spin excitation modes in isotropic ferromagnets. The data from EuS shows that the demagnetizing fields have a profound effect on the spin excitations below and above TC. In particular they prevent the long-wavelength spin fluctuations δS {norm of matrix} q from diverging at TC. This behaviour is reflected in the dynamics of the paramagnetic fluctuations and the spin waves below TC. The modes with longitudinal polarization are more damped than their transverse counterparts. Above TC the relaxation rates follow rather precisely the dipolar dynamic scaling functions calculated recently by mode-coupling theory. Below TC, the parallel magnetization fluctuations, δS {norm of matrix} M, are significantly stronger in EuS than in Ni.

AB - By means of polarized neutrons it is possible to measure different magnetic spin excitation modes in isotropic ferromagnets. The data from EuS shows that the demagnetizing fields have a profound effect on the spin excitations below and above TC. In particular they prevent the long-wavelength spin fluctuations δS {norm of matrix} q from diverging at TC. This behaviour is reflected in the dynamics of the paramagnetic fluctuations and the spin waves below TC. The modes with longitudinal polarization are more damped than their transverse counterparts. Above TC the relaxation rates follow rather precisely the dipolar dynamic scaling functions calculated recently by mode-coupling theory. Below TC, the parallel magnetization fluctuations, δS {norm of matrix} M, are significantly stronger in EuS than in Ni.

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JO - Physica B: Condensed Matter

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ER -

Spin fluctuations in isotropic ferromagnets near T_C

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