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Real-space visualization of short-range antiferromagnetic correlations in a magnetically enhanced thermoelectric
Matter ( IF 18.9 ) Pub Date : 2022-04-25 , DOI: 10.1016/j.matt.2022.03.011
Raju Baral , Jacob A. Christensen , Parker K. Hamilton , Feng Ye , Karine Chesnel , Taylor D. Sparks , Rosa Ward , Jiaqiang Yan , Michael A. McGuire , Michael E. Manley , Julie B. Staunton , Raphaël P. Hermann , Benjamin A. Frandsen

Short-range magnetic correlations can significantly increase the thermopower of magnetic semiconductors, representing a noteworthy development in the decades-long effort to develop high-performance thermoelectric materials. Here, we reveal the nature of the thermopower-enhancing magnetic correlations in the antiferromagnetic semiconductor MnTe. Using magnetic pair distribution function analysis of neutron-scattering data, we obtain a detailed, real-space view of robust, nanometer-scale, antiferromagnetic correlations that persist into the paramagnetic phase above the Néel temperature TN = 307 K. The magnetic correlation length in the paramagnetic state is significantly longer along the crystallographic c axis than within the ab plane, pointing to anisotropic magnetic interactions. Ab initio calculations of the spin-spin correlations using density functional theory in the disordered local moment approach reproduce this result with quantitative accuracy. These findings constitute the first real-space picture of short-range spin correlations in a magnetically enhanced thermoelectric and inform future efforts to optimize thermoelectric performance by magnetic means.



中文翻译:

磁增强热电中短程反铁磁相关性的实空间可视化

短程磁相关可以显着增加磁性半导体的热电势,这代表了几十年来开发高性能热电材料的显着进展。在这里,我们揭示了反铁磁半导体 MnTe 中增强热电势的磁相关性的性质。使用中子散射数据的磁对分布函数分析,我们获得了稳健的纳米级反铁磁相关性的详细实空间视图,这些相关性在 Néel 温度T N = 307 K 以上持续进入顺磁相。磁相关长度在顺磁状态下,沿晶体学c轴的长度明显长于在ab内平面,指向各向异性磁相互作用。在无序局部矩方法中使用密度泛函理论从头算计算自旋-自旋相关性以定量准确度再现了该结果。这些发现构成了磁增强热电中短程自旋相关性的第一张真实空间图片,并为未来通过磁手段优化热电性能的努力提供了信息。

更新日期:2022-04-25
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