Matsuda Takuya, Kanda Natsuki, Higo Tomoya, Armitage N P, Nakatsuji Satoru, Matsunaga Ryusuke
The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba, 277-8581, Japan.
CREST, Japan Science and Technology Agency, Kawaguchi, Saitama, 332-0012, Japan.
Nat Commun. 2020 Feb 14;11(1):909. doi: 10.1038/s41467-020-14690-6.
Antiferromagnetic spin motion at terahertz (THz) frequencies attracts growing interests for fast spintronics, however, their smaller responses to external field inhibit device application. Recently the noncollinear antiferromagnet MnSn, a Weyl semimetal candidate, was reported to show large anomalous Hall effect (AHE) at room temperature comparable to ferromagnets. Dynamical aspect of such large responses is an important issue to be clarified for future THz data processing. Here the THz anomalous Hall conductivity in MnSn thin films is investigated by polarization-resolved spectroscopy. Large anomalous Hall conductivity [Formula: see text] at THz frequencies is clearly observed as polarization rotation. A peculiar temperature dependence corresponding to the breaking/recovery of symmetry in the spin texture is also discussed. Observation of the THz AHE at room temperature demonstrates the ultrafast readout for the antiferromagnetic spintronics using MnSn, and will also open new avenue for studying nonequilibrium dynamics in Weyl antiferromagnets.
太赫兹（THz）频率下的反铁磁自旋运动因快速自旋电子学而受到越来越多的关注，然而，它们对外部场的较小响应阻碍了器件应用。最近，非共线反铁磁体MnSn，一种潜在的外尔半金属，被报道在室温下表现出与铁磁体相当的大反常霍尔效应（AHE）。对于未来的太赫兹数据处理而言，这种大响应的动力学方面是一个有待阐明的重要问题。在此，通过偏振分辨光谱研究了MnSn薄膜中的太赫兹反常霍尔电导率。太赫兹频率下的大反常霍尔电导率[公式：见正文]作为偏振旋转被清晰地观测到。还讨论了与自旋纹理中对称性的破坏/恢复相对应的特殊温度依赖性。在室温下对太赫兹反常霍尔效应的观测证明了使用MnSn的反铁磁自旋电子学的超快读出，并且还将为研究外尔反铁磁体中的非平衡动力学开辟新途径。
