Theory of Temperature-Dependent Magnon-Energies in Antiferromagnets : Magnetic Field Effect

概要

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The effect of the magnetic field on the magnon energy in antiferromagnets is studied by use of the random phase approximation of the spin wave theory, which was developed by the present authors. The temperature dependence of the spin-flop critical field H_c and parallel susceptibility χ_〃 if uniaxial antiferromagnets is calculated. It is shown that the present theory H_c reduce to the phenomenological theory in the small anisotropy energy limit. The theory is compared with the experiment on MnF_2. The experimental data of χ_〃 is reasonably explained by the theory, while the agreement between theory and experiment is rather poor in the case of H_c. Also, the perpendicular susceptibility is calculated by applying the present theory to Kanamori and Yosida's theory. It is found that the present approximation does not take into account the fluctuation of the exchange torque, which was considered by Kanamori and Itoh.
理論物理学刊行会の論文
1971-04-25