Longitudinal spin fluctuations (hidden magnetic excitations) in Invar alloys

Valiev, É. Z.; Menshikov, A.Z.

doi:10.1016/0304-8853(95)00037-2

Cited by 6 publications

(4 citation statements)

References 11 publications

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“…The three-peak structure is in agreement with the theoretical calculations of Valiev and Menshikov 13 and with the experimental data of Lynn et al 6 If we neglect the LSF, then the magnon damping would be equal to ⌫ s ϭ2␥ k 11 , i.e., to the transverse spin wave damping which is much smaller compared with Eq. ͑11͒.…”

supporting

confidence: 88%

“…The spin dynamics of the Invar alloys has not been studied intensively. Recently Valiev and Menshikov 13 have calculated the frequency-impulse spectrum of longitudinal spin fluctuations, which shows a three-peak structure. In order to understand and to elucidate the different contributions to the dynamics of the Invar alloys we have carried out a detailed study of this system using a Green's function technique of Tserkovnikov.…”

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confidence: 99%

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Theoretical study of the spin dynamics in Fe-Ni Invar alloys

Wesselinowa

1997

Phys. Rev. B

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A Green's function technique is used to study the spin dynamics in the Invar alloys. The longitudinal dynamical structure factor has been calculated. It exhibits a three-peak structure: two peaks due to magnetovolume interactions and a central peak due to the coupling of the transverse mode and the longitudinal relaxing mode. The dependence of the three peaks on temperature T, wave vector k, magnetic field H, and Ni concentration is discussed. The results are in good agreement with the experimental data for the Fe-Ni Invar alloys.

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confidence: 88%

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confidence: 99%

Theoretical study of the spin dynamics in Fe-Ni Invar alloys

Wesselinowa

1997

Phys. Rev. B

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“…Equation (35) demonstrates that the thermal demagnetization of the spontaneous magnetization is faster in spin systems in which, besides magnons, diffusons contribute [38] to the T 3/2dependence of M(T , 0). However, unlike magnons, diffusons show up as a broad central (elastic) peak [37] in the inelastic neutron scattering (INS) intensity versus neutron energy isotherms taken at constant values of q.…”

Section: Thermally Excited Spin Fluctuations 221 Low Temperatures At ...mentioning

confidence: 99%

“…Equation ( 41) is an alternative form of equation ( 38) obtained by replacing κ ν in equation (38) by…”

Section: Temperatures Outside the Critical Region But Not Very Far Fr...mentioning

confidence: 99%

Spin-fluctuation theory for weak itinerant-electron ferromagnets: revisited

Kaul

1999

J. Phys.: Condens. Matter

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An explicit self-consistent calculation of the zero-point (ZP) and thermally excited (TE) contributions to spin fluctuations in weak itinerant-electron (WI) ferromagnets in the presence and absence of an external magnetic field, based on the version of spin-fluctuation theory that makes use of the Ginzburg-Landau formalism, is presented. These calculations get rid of certain major deficiencies of the conventional spin-fluctuation theories by bringing out clearly the roles of ZP and TE excitations. The results so obtained demonstrate that zero-point spin fluctuations have a major share in renormalizing the Landau coefficients of the Stoner theory, are relatively insensitive to magnetic field, and make an appreciable contribution to the temperature dependence of magnetization in WI ferromagnets. By contrast, thermally excited collective electron-hole pair excitations almost entirely account for the dependences of magnetization on temperature and field, and get strongly suppressed by magnetic field. The present theoretical approach, in addition, for the first time, yields an analytical expression for the suppression of thermally excited spin fluctuations by field for temperatures just outside the critical region but below the Curie point.

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Phase Transitions and Finite Temperature Magnetism: Experiment and Analysis

Kaul

2007

Handbook of Magnetism and Advanced Magnetic Materials

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Magnetic excitations, prevailing in different temperature regimes that lie below the magnetic ordering temperature, and static critical phenomena near the thermally‐driven magnetic order–disorder phase transitions in spin systems in which the electrons responsible for magnetism are either localized or itinerant are reviewed from the experimental point of view. Besides bringing out clearly the importance of the energy and time scales governing various physical processes connected with the finite temperature magnetism and phase transitions in such systems, a brief account of the relevant theoretical background and crucial steps in the data analyses is given so as to prepare the ground for a meaningful comparison between theory and experiment. Such a comparison, in turn, is shown to provide improved understanding of the nature and origin of magnetic excitations and critical phenomena in localized‐spin and itinerant‐electron systems. In addition, this review highlights both the power as well as the limitations of the experimental techniques employed in the literature to study magnetic excitations and deals extensively with the magnon‐to‐fracton crossover in systems with localized spins and crossovers between different critical regimes in isotropic spin systems with long‐range interactions or spin systems in which long‐range interactions occur in association with magnetic anisotropy.

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Longitudinal spin fluctuations (hidden magnetic excitations) in Invar alloys

Cited by 6 publications

References 11 publications

Theoretical study of the spin dynamics in Fe-Ni Invar alloys

Theoretical study of the spin dynamics in Fe-Ni Invar alloys

Spin-fluctuation theory for weak itinerant-electron ferromagnets: revisited

Phase Transitions and Finite Temperature Magnetism: Experiment and Analysis

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