Green Function Theory of Temperature Dependence of Spin-Wave Impurity Modes in Heisenberg Antiferromagnets

概要

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Within the random phase approximation, the Green functions are obtained in Heisenberg antiferromagnets doped with impurities. In order to understand the temperature dependence of spin-wave impurity modes intuitively, the local energy renormalization factors are introduced which play a role of an effective field for individual spin. Dimension of the eigenvalue matrix of impurity modes is reduced to (z+1)×(z+1) from 2N×2N by introducing an appropriate approximation. Here, z and N represent the coordination number and the number of ions in one sublattice, respectively, Numerical calculations of the Green functions and spin correlations are carried out self-consistently. Magnetizations of impurity and its nearest neighbor ions, energy eigenvalues of the localized modes and energy spectra of the resonant modes are calculated as functions of temperature for various values of the impurity-host exchange coupling J' and the impurity spin S' in a simple cubic antiferromagnet with S=5/2.
社団法人日本物理学会の論文
1972-02-05