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Paramagnetic resonance linebroadening and spin--spin relaxation near magnetic critical points

Conference · · AIP (Am. Inst. Phys.) Conf. Proc., no. 24, pp. 261-267
OSTI ID:4135844
Recent studies of EPR linewidths near critical points in magnetic insulators are reviewed. Behavior of representative three-dimensional antiferromagnets RbMnF$sub 3$, MnF$sub 2$, NiCl$sub 2$, MnO, and MnS and ferromagnets EuO and CrBr$sub 3$ is analyzed. The connection between the EPR linewidth and the relaxation rate of the fluctuations in the total magnetization in zero field is established. Symmetry arguments are used to confirm the hypothesis that the anomalies in the EPR linewidth arise from a coupling between the fluctuations in the total magnetization and the long wavelength fluctuations in the order parameter. This coupling is induced by anisotropic terms in the Hamiltonian. The dependence of the linewidth on temperature and on the direction and magnitude of the applied field is discussed. The contribution to the linewidth coming from the spin-phonon interaction is also considered. (9 figures, 33 references) (auth)
Research Organization:
West Virginia Univ., Morgantown
NSA Number:
NSA-33-003442
OSTI ID:
4135844
Conference Information:
Journal Name: AIP (Am. Inst. Phys.) Conf. Proc., no. 24, pp. 261-267
Country of Publication:
United States
Language:
English