混合磁性薄膜矫顽力及阶梯效应的微磁学及Monte Carlo研究

采用能量极小原理的微磁学及Monte Carlo方法对铁磁/反铁磁混合磁性薄膜的磁特性进行了模拟计算，研究了基态下系统的磁滞回线、自旋组态及铁磁交换作用常数JAA、单轴各向异性常数K、偶极相互作用常数D和铁磁性原子掺杂量X对矫顽力Hc的影响. 同时还模拟计算了矫顽力Hc的温度特性.模拟结果表明，在混合磁性薄膜中磁滞回线存在明显的阶梯效应，利用简单的Ising模型揭示这种阶梯效应主要起源于包含不同反铁磁原 子的掺杂量的不同尺寸的原子团对外加磁场所产生不同响应；在基态下当0.5≤X≤1.0时矫顽力Hc随K，J 关键词： 蒙特卡罗 微磁学 阶梯效应 混合磁系统 矫顽力

Study on the coercivity and step effect of mixed magnetic films by micromagnetism and Monte Carlo simulation

The magnetic properties of ferromagnetically and antiferromagnetically mixed fi lms are simulated by micromagnetism method based on the principle of energy mini mum and Monte Carlo technology. The hysteresis loops, spin configurations, and the influences of exchange constant JAA, uniaxial anisotropy constant K, dipolar interaction constant Dand diluted ratio of ferromagnetic ato m X on the coercivity Hc at the ground states are studied systematical ly for the systems studied. A t the same time, the temperature dependence of the coercivity is calculated. The simulated results indicate that: (1) a steplike hysteresis is evidently observed in the mixed magnetic films, and the result calculated by a simple Ising model reveals that the step like effect can be attributed to the different response of the clusters with different size and different diluted ratio of antiferromagn etic atom on the external field; (2) at the ground states, as 0.5≤X≤1.0,the value of Hc increases with increasing values ofK, JAA, but decreases with increasing value of D; (3) a peak exists in the Hc X curves. These simulated resu lts explain the experimental facts about the granular films with antiferromagnetic coupling. The T dependence of the value ofHc for the films with diffe rent magnitude of X can be well described by the law of Tα. But the value of α has a complex variation with the change of X.