发表机构
Instituto de Ciencia de Materiales de Madrid, CSIC; Hitachi Cambridge Laboratory; HUN-REN Wigner Research Centre for Physics; Budapest University of Technology and Economics（马德里材料科学研究所，西班牙国家科学研究委员会; 日立剑桥实验室; 匈牙利研究网络维格纳物理研究中心; 布达佩斯技术与经济大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过格林函数理论计算双子格铁磁体的有效自旋模型参数温度依赖性，发现不等效热重整化导致自旋波刚度非单调变化，并与原子自旋动力学模拟定量一致，为有限温度微磁建模提供关键参数。
AI 中文摘要
我们利用格林函数理论计算了具有反平行且不等效子格磁化强度的双子格铁磁体中有效自旋模型参数的温度依赖性。有效的子格内和子格间交换相互作用以及子格各向异性表现出不同的热重整化，这源于两个子格不同的磁相互作用和关联。尽管这些有效相互作用参数随温度升高而单调减小，但它们的不等重整化产生了强非单调且偏振依赖的长波长自旋波响应。特别是，自旋波交换刚度表现出强支依赖且非单调的温度依赖性。一种偏振在角动量补偿区域附近发展出增强的自旋波刚度，尽管底层交换相互作用单调热减小。格林函数预测与原子自旋动力学模拟定量一致，后者提供了包括底层原子自旋模型内热诱导自旋关联的数值基准。这些结果建立了温度依赖的原子相互作用、长波长自旋波刚度以及铁磁材料有限温度微磁和多尺度建模所需有效参数之间的直接联系。
英文摘要
We compute the temperature dependence of effective spin-model parameters in two-sublattice ferrimagnets with antiparallel and inequivalent sublattice magnetizations using Green's-function theory. The effective intra- and intersublattice exchange interactions, together with the sublattice anisotropies, exhibit distinct thermal renormalizations arising from the different magnetic interactions and correlations of the two sublattices. Although these effective interaction parameters decrease monotonically with increasing temperature, their unequal renormalization produces a strongly nonmonotonic and polarization-dependent long-wavelength spin-wave response. In particular, the spin-wave exchange stiffness exhibits a strongly branch-dependent and nonmonotonic temperature dependence. One polarization develops an enhanced spin-wave stiffness in the vicinity of the angular momentum compensation region despite the monotonic thermal reduction of the underlying exchange interactions. The Green's-function predictions are in quantitative agreement with atomistic spin-dynamics simulations, which provide a numerical benchmark including thermally induced spin correlations within the underlying atomistic spin model. These results establish a direct connection between temperature-dependent atomistic interactions, long-wavelength spin-wave stiffness, and the effective parameters required for finite-temperature micromagnetic and multiscale modeling of ferrimagnetic materials.
Comments19 pages, 7 figures
