Liu Yizhou, Holder Tobias, Yan Binghai
Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 76100, Israel.
Innovation (Camb). 2021 Feb 28;2(1):100085. doi: 10.1016/j.xinn.2021.100085.
Twisted bilayer graphene (TBG) exhibits fascinating correlation-driven phenomena like the superconductivity and Mott insulating state, with flat bands and a chiral lattice structure. We find by quantum-transport calculations that the chirality leads to a giant unidirectional magnetoresistance (UMR) in TBG, where the unidirectionality refers to the resistance change under the reversal of the direction of current or magnetic field. We point out that flat bands significantly enhance this effect. The UMR increases quickly upon reducing the twist angle, and reaches about 20% for an angle of 1.5° in a 10 T in-plane magnetic field. We propose the band structure topology (asymmetry), which leads to a direction-sensitive mean free path, as a useful way to anticipate the UMR effect. The UMR provides a probe for chirality and band flatness in the twisted bilayers.
扭曲双层石墨烯（TBG）展现出诸如超导性和莫特绝缘态等迷人的关联驱动现象，具有平带和手性晶格结构。我们通过量子输运计算发现，手性导致了TBG中巨大的单向磁阻（UMR），其中单向性是指电流或磁场方向反转时的电阻变化。我们指出，平带显著增强了这种效应。随着扭曲角减小，UMR迅速增加，在10 T面内磁场中，对于1.5°的角度，UMR达到约20%。我们提出能带结构拓扑（不对称性），它导致方向敏感的平均自由程，作为预测UMR效应的一种有用方法。UMR为扭曲双层中的手性和平带提供了一种探测手段。
