Real-space visualization of short-range antiferromagnetic correlations in a magnetically enhanced thermoelectric
Real-space visualization of short-range antiferromagnetic correlations in a magnetically enhanced thermoelectric
复制标题
DOI：
10.1016/j.matt.2022.03.011
复制
发表时间：
2022-01
期刊：
影响因子：
18.9
通讯作者：
R. Baral;Jacob Christensen;Parker K. Hamilton;F. Ye;K. Chesnel;Taylor D. Sparks;Rosa Ward;Jiaqiang Yan;M. McGuire;M. Manley;J. Staunton;R. Hermann;B. Frandsen
中科院分区：
文献类型：
--
作者：
R. Baral;Jacob Christensen;Parker K. Hamilton;F. Ye;K. Chesnel;Taylor D. Sparks;Rosa Ward;Jiaqiang Yan;M. McGuire;M. Manley;J. Staunton;R. Hermann;B. Frandsen
短程磁关联可以显着提高磁性半导体的热电势，这是数十年来开发高性能热电材料的一个值得注意的进展。在这里，我们揭示了反铁磁半导体 MnTe 中热电增强磁关联的本质。利用中子散射数据的磁对分布函数分析，我们获得了鲁棒、纳米级反铁磁相关性的详细、真实空间视图，这些相关性在尼尔温度TN = 307 K以上的顺磁相中持续存在。顺磁状态下的磁相关长度沿着晶轴比在ab平面内明显更长，这表明磁相互作用各向异性。 在无序局部矩方法中使用密度泛函理论对自旋-自旋相关性进行的初始计算可以定量准确地重现该结果。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，并为未来通过磁性手段优化热电性能的努力提供了信息。
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 temperatureTN= 307 K. The magnetic correlation length in the paramagnetic state is significantly longer along the crystallographiccaxis than within theabplane, pointing to anisotropic magnetic interactions.Ab initiocalculations 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.