(1) Department of Applied Physics, National University of Kaohsiung, Kaohsiung, 811, Taiwan, ROC;(2) Department of Physics, National Tsing-Hua University, Hsinchu 300, National Center for Theoretical Science, Hsinchu, 300, Taiwan
Abstract:
Employing the self-consistent Green's function approach, we
studied the temperature dependence of the spin-wave stiffness in
diluted magnetic semiconductors. Note that the Green's function
approach includes the spatial and temperature fluctuations
simultaneously which was not possible within conventional Weiss
mean-field theory. It is rather interesting that we found the
stiffness becomes dramatically softened as the critical
temperature is approached, which seems to explain the mysterious
sharp drop of magnetization curves in samples within diffusive
regime.