• 文献标题:   Coexistence and competition of nematic and gapped states in bilayer graphene
  • 文献类型:   Article
  • 作  者:   GORBAR EV, GUSYNIN VP, MIRANSKY VA, SHOVKOVY IA
  • 作者关键词:  
  • 出版物名称:   PHYSICAL REVIEW B
  • ISSN:   1098-0121
  • 通讯作者地址:   Taras Shevchenko Natl Kiev Univ
  • 被引频次:   16
  • DOI:   10.1103/PhysRevB.86.125439
  • 出版年:   2012

▎ 摘  要

In bilayer graphene, the phase diagram in the plane of a strain-induced bare nematic term N-0 and a top-bottom gates voltage imbalance U-0 is obtained by solving the gap equation in the random-phase approximation. At nonzero N-0 and U-0, the phase diagram consists of two hybrid spin-valley symmetry-broken phases with both nontrivial nematic and mass-type order parameters. The corresponding phases are separated by a critical line of first- and second-order phase transitions at small and large values of N-0, respectively. The existence of a critical end point where the line of first- order phase transitions terminates is predicted. For N-0 = 0, a pure gapped state with a broken spin-valley symmetry is the ground state of the system. As N-0 increases, the nematic order parameter increases, and the gap weakens in the hybrid state. For U-0 = 0, a quantum second-order phase transition from the hybrid state into a pure gapless nematic state occurs when the strain reaches a critical value. A nonzero U-0 suppresses the critical value of the strain. The relevance of these results to recent experiments is briefly discussed.