The longitudinal susceptibility, a measure of magnetization fluctuations, is studied within the framework of the Dyson Hamiltonian. Results for models appropriate to EuO and EuS show that, near T(c), the fluctuations included in the Hartree-Fock approximation more than double the susceptibility. It is shown that inclusion of the fluctuations does not change the exponent in the power law divergence of the susceptibility with respect to a magnetic field. Results for the magnetization and spin-wave renormalization, including the influence of the dipolar energy, are given for EuO and EuS, and compared favourably with the available experimental data.
SPIN-DENSITY FLUCTUATIONS IN A HEISENBERG-FERROMAGNET / A. CUCCOLI; S.W. LOVESEY; G. PEDROLLI; V. TOGNETTI. - In: JOURNAL OF PHYSICS. CONDENSED MATTER. - ISSN 0953-8984. - STAMPA. - 5:(1993), pp. 3241-3252. [10.1088/0953-8984/5/19/020]
SPIN-DENSITY FLUCTUATIONS IN A HEISENBERG-FERROMAGNET
CUCCOLI, ALESSANDRO;TOGNETTI, VALERIO
1993
Abstract
The longitudinal susceptibility, a measure of magnetization fluctuations, is studied within the framework of the Dyson Hamiltonian. Results for models appropriate to EuO and EuS show that, near T(c), the fluctuations included in the Hartree-Fock approximation more than double the susceptibility. It is shown that inclusion of the fluctuations does not change the exponent in the power law divergence of the susceptibility with respect to a magnetic field. Results for the magnetization and spin-wave renormalization, including the influence of the dipolar energy, are given for EuO and EuS, and compared favourably with the available experimental data.
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