基于线性响应形式的Gilbert阻尼参数的第一性原理计算及其在磁性过渡金属和合金中的应用
First-principles calculation of the Gilbert damping parameter via the linear response formalism with application to magnetic transition-metals and alloys
摘要：
本文提出了一种基于线性响应理论，结合相干势近似合金理论，在完全相对论Korringa-Kohn-Rostoker能带结构方法中计算Gilbert阻尼参数$α$的方法。为了解释作为散射机制的原子的热位移，引入合金类模型。这允许确定$α$的各种类型的材料，如元素磁性系统和有序的磁性化合物在有限的温度下，以及无序的磁性合金在$T = 0$ K和以上。分析了自旋轨道耦合、化学和温度引起的结构无序的影响。计算了3种$d$过渡金属bcc Fe、hcp Co和fcc Ni及其二元合金bcc Fe $_{1-x}$ Co $_{x}$、fcc Ni $_{1-x}$ Fe $_x$、fcc Ni $_{1-x}$ Co $_x$和bcc Fe $_{1-x}$ V $_{x}$以及过渡金属合金中的5 d杂质。所得结果与实验结果吻合较好。
英文摘要：
A method for the calculations of the Gilbert damping parameter $α$ is presented, which based on the linear response formalism, has been implemented within the fully relativistic Korringa-Kohn-Rostoker band structure method in combination with the coherent potential approximation alloy theory. To account for thermal displacements of atoms as a scattering mechanism, an alloy-analogy model is introduced. This allows the determination of $α$ for various types of materials, such as elemental magnetic systems and ordered magnetic compounds at finite temperature, as well as for disordered magnetic alloys at $T = 0$ K and above. The effects of spin-orbit coupling, chemical and temperature induced structural disorder are analyzed. Calculations have been performed for the 3$d$ transition-metals bcc Fe, hcp Co, and fcc Ni, their binary alloys bcc Fe$_{1-x}$Co$_{x}$, fcc Ni$_{1-x}$Fe$_x$, fcc Ni$_{1-x}$Co$_x$ and bcc Fe$_{1-x}$V$_{x}$, and for 5d impurities in transition-metal alloys. All results are in satisfying agreement with experiment.
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