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arXiv · 1211.3802

Topological phases in gated bilayer graphene: Effects of Rashba spin-orbit coupling and exchange field

Zhenhua Qiao·Xiao Li·Wang-Kong Tse·Hua Jiang·Yugui Yao·Qian Niu
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Abstract

We present a systematic study on the influence of Rashba spin-orbit coupling, interlayer potential difference and exchange field on the topological properties of bilayer graphene. In the presence of only Rashba spin-orbit coupling and interlayer potential difference, the band gap opening due to broken out-of-plane inversion symmetry offers new possibilities of realizing tunable topological phase transitions by varying an external gate voltage. We find a two-dimensional $Z_2$ topological insulator phase and a quantum valley Hall phase in $AB$-stacked bilayer graphene and obtain their effective low-energy Hamiltonians near the Dirac points. For $AA$ stacking, we do not find any topological insulator phase in the presence of large Rashba spin-orbit coupling. When the exchange field is also turned on, the bilayer system exhibits a rich variety of topological phases including a quantum anomalous Hall phase, and we obtain the phase diagram as a function of the Rashba spin-orbit coupling, interlayer potential difference, and exchange field.

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Zhenhua Qiao, Xiao Li, Wang-Kong Tse, Hua Jiang, Yugui Yao, Qian Niu. 2012-11-16. Topological phases in gated bilayer graphene: Effects of Rashba spin-orbit coupling and exchange field. https://doi.org/10.1103/physrevb.87.125405

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