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arXiv 2006.02752cond-mat.mes-hallcond-mat.mtrl-sciphysics.app-phquant-ph
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反铁磁拓扑绝缘体异质结构的反常磁光效应

Anomalous Magneto Optic Effects from an Antiferromagnet Topological-Insulator Heterostructure

Amrit De, Tonmoy K. Bhowmick, Roger Lake

摘要:

没有净磁化的材料通常不是磁光活性的。虽然这是单独为真的共线反铁磁体(AFM)和拓扑绝缘体(TI),它在这里示出的磁光克尔效应(MOKE)出现时,TI和AFM膜接近耦合。由于缺乏宏观磁化,AFM只耦合到TI表面之一的自旋,打破了时间反转和反转对称性-这导致了一个微小的$μ$度MOKE信号。这种小MOKE可以很容易地增强5个数量级,通过腔谐振,通过优化AFM和TI膜厚度的基板上。对于稍微偏离共振的结构,6度克尔旋转可以通过改变费米能量来电切换。这需要小于20 meV,这对于低功率自旋电子学和磁光器件是令人鼓舞的。我们进一步表明,这种简单的结构很容易恢复到5%的材料生长误差。

英文摘要:

Materials with no net magnetization are generally not magneto-optically active. While this is individually true for a collinear antiferromagnet (AFM) and a topological insulator (TI), it is shown here that the magneto-optic Kerr effect (MOKE) emerges when the TI and AFM films are proximity coupled. Because of the lack of macroscopic magnetization, the AFM only couples to the spin of one of the TI's surfaces breaking time-reversal and inversion symmetry -- which leads to a tiny $μ$deg MOKE signal. This small MOKE can be easily enhanced by 5 orders of magnitude, via cavity resonance, by optimizing the AFM and TI film thicknesses on the substrate. For slightly off-resonant structures, a 6 deg Kerr rotation can be electrically switched on by varying the Fermi energy. This requires less than 20 meV, which is encouraging for low power spintronics and magneto-optic devices. We further show that this simple structure is easily resilient to 5% material growth error.

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