• 文献标题:   Landau level phases in bilayer graphene under pressure at charge neutrality
  • 文献类型:   Article
  • 作  者:   GREEN BR, SOFO JO
  • 作者关键词:  
  • 出版物名称:   PHYSICAL REVIEW B
  • ISSN:   2469-9950 EI 2469-9969
  • 通讯作者地址:   Penn State Univ
  • 被引频次:   0
  • DOI:   10.1103/PhysRevB.101.195432
  • 出版年:   2020

▎ 摘  要

Bilayer graphene in a magnetic field hosts a variety of ordered phases built from eight Landau levels close in energy to the neutrality point. These (l)evels are characterized by orbital n = 0, 1, valley xi = +, -, and spin sigma = up arrow, down arrow; their relative energies depend strongly on the Coulomb interaction, magnetic field, and interlayer bias. We treat interactions at the Hartree-Fock level, including the effects of metallic gates, layer separation, spatial extent of the p(z) orbitals, all Slonczewski-Weiss-McClure tight-binding parameters, and pressure. We obtain the ground state as function of the applied magnetic field, bias, and pressure. The gates, layer separation, and extent of the p(z) orbitals weaken the Coulomb interaction at different length scales; these effects distort the phase diagram but do not change its topology. However, previously predicted continuous transitions become discontinuous when all tight-binding parameters are included nonperturbatively. We find that pressure increases the importance of the noninteracting scale with respect to the Coulomb energy, which drives phase transitions to occur at lower fields. This brings two orbitally polarized states not yet predicted or observed into the experimentally accessible region of the phase diagram, in addition to previously identified valley-polarized, spin-polarized, and partially orbitally polarized states.