HYSTERESIS IN A MEAN-FIELD SPIN MODEL: OSCILLATION BEHAVIOR AND NEGATIVE ENERGY DISSIPATION

Abstract

For a mean-field ferromagnetic Ising system subject to a rotating transverse external field and a bath, the hysteresis loop area is studied by a complete analytical solution of the equation of motion of magnetization. In any cycle, the loop area is proportional to the field when the field strength is small and oscillates when the field strength is strong. The oscillation comes from the modulation of the behavior of magnetization with a frequency related to the field strength, which is caused by interaction between the Ising system and the bath. In the oscillation regime, the loop area can be negative except in the first cycle.