论文标题
从磁性限制的超级电池开始计算材料的磁性吉布斯自由能
Ab initio calculation of the magnetic Gibbs free energy of materials using magnetically constrained supercells
论文作者
论文摘要
我们提出了一种使用磁性约束的超级细胞计算来计算材料的磁性吉布斯自由能的第一原理方法。我们的方法基于慢慢变化的局部力矩取向的绝热近似，即所谓的有限温度无序的局部力矩图片。它描述了磁相跃迁以及电子和/或磁结构机制如何产生不连续的（一阶）字符。我们证明，局部力矩方向的统计力学可以通过负担得起的超级电池计算来描述，这些超级电池计算含有非连接磁性构型。通过首先研究BCC FE中的铁磁状态，可以说明我们方法的适用性。然后，我们研究了两个Antiperovskite Systems Mn $ _3 $ a（a = ga，ni）中三角形抗磁磁状态稳定的温度依赖性特性。我们的计算提供了这些材料的负容量的膨胀，以及相变（电子和/或磁结构）不连续特征的从头开始，与实验良好一致。
We present a first-principles approach for the computation of the magnetic Gibbs free energy of materials using magnetically constrained supercell calculations. Our approach is based on an adiabatic approximation of slowly varying local moment orientations, the so-called finite-temperature disordered local moment picture. It describes magnetic phase transitions and how electronic and/or magnetostructural mechanisms generate a discontinuous (first-order) character. We demonstrate that the statistical mechanics of the local moment orientations can be described by an affordable number of supercell calculations containing noncollinear magnetic configurations. The applicability of our approach is illustrated by firstly studying the ferromagnetic state in bcc Fe. We then investigate the temperature-dependent properties of a triangular antiferromagnetic state stabilizing in two antiperovskite systems Mn$_3$AN (A = Ga, Ni). Our calculations provide the negative volume expansion of these materials as well as the ab initio origin of the discontinuous character of the phase transitions, electronic and/or magnetostructural, in good agreement with experiment.
