缺陷对滞后标度性的影响

对二维Ising铁磁系统中的非磁杂质，利用Monte Carlo方法，获得不同杂质浓度、不同磁场变化速率下的磁滞(?)线，从而得到滞后(?)线面积与磁场变化速率的关系．结果表明，在温度和缺陷浓度组成的相图上，存在一条相变线．低温和低浓度时，(?)线面积与磁场速率的标度指数约为1/3，只微弱地依赖于温度及杂质浓度；而对高温和高浓度的杂质，指数强烈地依赖于温度和浓度关键词：

DYNAMIC SCALING OF HYSTERESIS IN THE 2D ISING MODEL WITH IMPURITIES

As impurities always plague real experiments,we report here a study on the effect of impurity on the dynamic scaling behavior of hysteresis.The model used is the two -dimensional Ising model with quenched random non-magnetic impurities.The results show that for any temperature below the critical point,there exists a corresponding critical concentration of impurities that serves as the critical point in the pure model for distinguishing the scaling behavior of hysteresis.The hysteresis loop area A,representing the dissipation per cycle,scales with the scanning rate of the external field R as A=A₀+aRⁿ, with a nearly constant n～1/3, weakly dependent on the concentration,and a finite area A₀ even for vanishing small rates below the critical concentration.While above it, A₀=0 and n increases significantly with the concentration. This behavior is similar to the pure system.Thus in the concentration -temperature phase diagram there is a regime within which the scaling relation and its exponent of the pure system are robust with impurities.