Static thermodynamic quantities of quantum Heisenberg spin glasses with anisotropic interaction in applied magnetic fields.

In the static replica symmetric approximation, the quantum Heisenberg spin-glass model with the infinite-ranged random Dzyaloshinskii-Moriya interaction in external magnetic fields is investigated in detail. The local susceptibility and the corresponding order parameters are calculated, which are in good agreement with those of thermofield calculations. The dependencies of entropy and specific heat on temperature are studied numerically at various magnetic fields and for different spin numbers. It is shown that the entropy is always positive and the quantum fluctuation has very strong effect on specific heat. Our results show that the typical specific heat of a spin glass for different magnetic fields exhibits crossover behavior, which has been obtained experimentally but not explained theoretically before.