发表机构
National Institute for Materials Science; Research Institute for Interdisciplinary Science, Okayama University; Department of Advanced Materials Science, Graduate School of Frontier Sciences, The University of Tokyo（国立材料研究所; 冈山大学交叉科学研究所; 东京大学前沿科学研究生院先进材料科学系）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文观测到铁磁(Mn,Cr)Sb中由纵向自旋涨落驱动的能斯特效应，该效应在居里温度附近显现而反常霍尔效应消失，理论重现表明自旋涨落可成为能斯特效应的驱动力，为横向热电转换提供新途径。
AI 中文摘要
能斯特效应将热流转化为正交方向上的电荷流，通常分为两类：由施加于导体的外磁场引起的普通效应，以及由磁性材料中静态磁化引起的反常效应。因此，人们预期反常能斯特效应会随磁化强度在居里温度处消失。在此，我们观测到一种反而在居里温度附近显现的能斯特效应。在一系列铁磁(Mn,Cr)Sb样品中，能斯特系数即使在跨越居里温度时仍呈现有限值，而反常霍尔电阻率却消失，这表明Mott关系被破坏。这些存留的能斯特效应与消失的霍尔效应导致横向热电导率在居里温度附近出现峰值行为，我们通过引入自旋的纵向涨落从理论上重现了这一现象，而无需考虑奇异的自旋纹理、非平庸的电子结构或磁振子与声子拖曳效应。由纵向自旋涨落驱动的能斯特效应揭示出，不仅是静态磁有序，自旋涨落也可以成为磁性材料中能斯特效应的驱动力，为增强横向热电转换开辟了另一条途径。
英文摘要
The Nernst effect, which converts a heat current into a charge current in the orthogonal direction, is generally classified into the ordinary effect due to an external magnetic field applied to conductors and the anomalous effect due to static magnetization in magnetic materials. Thus, one expects that the anomalous Nernst effect disappears at the Curie temperature following the magnetization. Here, we observe the Nernst effect which rather manifests around the Curie temperature. In a series of ferromagnetic (Mn,Cr)Sb samples, the Nernst coefficients exhibit finite values even across the Curie temperatures, whereas the anomalous Hall resistivity disappears, suggesting the breakdown of the Mott relation. These surviving Nernst and vanishing Hall effects result in a peak behavior of the transverse thermoelectric conductivity around the Curie temperature, which we theoretically reproduce by introducing longitudinal fluctuations of spins without accounting for an exotic spin texture, a non-trivial electronic structure, or magnon- and phonon-drag effects. The Nernst effect driven by the longitudinal spin fluctuations reveals that not only the static magnetic order but also the spin fluctuations can be a driving force of the Nernst effect in magnetic materials, opening another way for boosting transverse thermoelectric conversion.
