Hall effects in artificially corrugated bilayer graphene without breaking time-reversal symmetry
Hall effects in artificially corrugated bilayer graphene without breaking time-reversal symmetry
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DOI：
10.1038/s41928-021-00537-5
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发表时间：
2021-02-01
影响因子：
34.3
通讯作者：
Chen, Tse-Ming
中科院分区：
文献类型：
--
作者：
Ho, Sheng-Chin;Chang, Ching-Hao;Chen, Tse-Ming
双层石墨烯中的人工波纹可以产生非线性的反常霍尔效应，这种效应源于Berry曲率偶极子，而线性霍尔效应源于弯曲的Rashba型谷轨道耦合带色散。应变可以用来改变二维材料的能带结构，从而改变其电子性质。然而，研究集中在使用单层石墨烯，其空间对称性有限降低，并且仅考虑实空间伪磁场。在这里，我们表明，光刻图案化的应变可以用来创建一个非平凡的带结构和奇异相的物质在双层石墨烯。该方法创建了人工波纹双层石墨烯，其中实空间和动量空间伪磁场（Berry曲率）共存，并具有非平凡的性质，如Berry曲率偶极子。这导致了两种霍尔效应的出现，而不破坏时间反演对称性：一种是非线性的异常霍尔效应，源于Berry曲率偶极子，以前只在Weyl半金属WTe 2中观察到，另一种是线性霍尔效应，源于Rashba谷轨道耦合顶部的弯曲带色散，类似于最近提出的马格努斯霍尔效应。
Artificial corrugations in bilayer graphene can produce a nonlinear anomalous Hall effect that originates from the Berry curvature dipole and a linear Hall effect that originates from a warped Rashba-like valley-orbit coupled band dispersion.Strain can be used to modify the band structure-and thus the electronic properties-of two-dimensional materials. However, research has focused on the use of monolayer graphene with a limited lowering of spatial symmetry and considered only the real-space pseudo-magnetic field. Here we show that lithographically patterned strain can be used to create a non-trivial band structure and exotic phase of matter in bilayer graphene. The approach creates artificially corrugated bilayer graphene in which real-space and momentum-space pseudo-magnetic fields (Berry curvatures) coexist and have non-trivial properties, such as Berry curvature dipoles. This leads to the appearance of two Hall effects without breaking time-reversal symmetry: a nonlinear anomalous Hall effect that originates from the Berry curvature dipole, previously only observed in the Weyl semimetal WTe2, and a linear Hall effect that originates from a warped band dispersion on top of Rashba-like valley-orbit coupling and is similar to the recently proposed Magnus Hall effect.