论文标题
纯和混合各向异性系统中两离子各向异性的温度缩放
Temperature scaling of two-ion anisotropy in pure and mixed anisotropy systems
论文作者
论文摘要
磁各向异性在磁性材料的信息技术应用中起着至关重要的作用，提供了一种在存在热波动的情况下保留磁状态的长期稳定性的手段。各向异性由源自晶体结构的单离子贡献和归因于磁原子之间的交换相互作用的两离子项组成。缺乏强大的理论在纯粹的两离子和混合单离子和两离子系统中对温度依赖性的理解至关重要。在这里，我们使用绿色的功能理论和原子蒙特卡洛模拟来确定在这些纯和混合病例中，从饱和到消失的磁化强度，在这些纯种和混合的情况下，铁磁体中有效的各向异性的温度缩放。在低温下，我们发现纯二离子各向异性尺度缩小为$ k（m）\ sim m^{2.28} $，而混合方案描述了在真实材料中观察到的各向异性的多样性。预计此处确定的混合各向异性的温度依赖性将极大地有助于理解和控制磁性材料的热性能。
Magnetic anisotropy plays an essential role in information technology applications of magnetic materials, providing a means to retain the long-term stability of a magnetic state in the presence of thermal fluctuations. Anisotropy consists of a single-ion contribution stemming from the crystal structure and two-ion terms attributed to the exchange interactions between magnetic atoms. A lack of robust theory crucially limits the understanding of the temperature dependence of the anisotropy in pure two-ion and mixed single-ion and two-ion systems. Here, we use Green's function theory and atomistic Monte Carlo simulations to determine the temperature scaling of the effective anisotropy in ferromagnets in these pure and mixed cases, from saturated to vanishing magnetization. At low temperature, we find that the pure two-ion anisotropy scales with the reduced magnetization as $k(m) \sim m^{2.28}$, while the mixed scenario describes the diversity of the temperature dependence of the anisotropy observed in real materials. The temperature dependence of the mixed anisotropy determined here is expected to considerably contribute to the understanding and the control of the thermal properties of magnetic materials.
