Temperature Dependence of Magnon Sideband

抄録

Temperature dependence of magnon sideband with respect to the intensity, shift and broadening is studied theoretically in the entire temperature range by using the moment expansion method. The assumption of the Néel state for the ground state of the antiferromagnets is reasonable for intensity and shift but is incapable of explaining the magnitude of the width.
Numerical calculations are carried out for ⁶A_1g→⁴A_1g, ⁴E_g transition of RbMnF₃ by means of the random phase decoupling approximation for spin correlation functions and the results are presented. The results agree with those of the spin wave theory at low temperatures. At the high temperature limit, both the intensity and shift also agree with those given by the pair spectra theory. The effect of exciton transfer is also considered. The numerical result of the shift is compared with experiments.