• 文献标题:   Why the first magic-angle is different from others in twisted graphene bilayers: Interlayer currents, kinetic and confinement energy, and wave-function localization
  • 文献类型:   Article
  • 作  者:   NAVARROLABASTIDA LA, ESPINOSACHAMPO A, AGUILARMENDEZ E, NAUMIS GG
  • 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:  
  • 被引频次:   6
  • DOI:   10.1103/PhysRevB.105.115434
  • 出版年:   2022

▎ 摘  要

The chiral Hamiltonian for twisted graphene bilayers is analyzed in terms of its squared Hamiltonian which removes the particle-hole symmetry and thus one bipartite lattice, allowing us to write the Hamiltonian in terms of a 2??2 matrix. This brings to the front the three main physical actors of twisted systems: kinetic energy, confinement potential, and an interlayer interaction operator which is divided in two parts: a non-Abelian interlayer operator and an operator which contains an interaction energy between layers. Here, each of these components is analyzed as a function of the angle of rotation as well as in terms of the wave-function localization properties. It is proved that the non-Abelian operator represents interlayer currents between each layer of triangular sublattices, i.e., a second-neighbor interlayer current between bipartite sublattices. A crossover is seen between such contributions, and thus, the first magic-angle is different from other higher-order magic-angles. Such angles are determined by a balance between the negative energy contribution from interlayer currents and the positive contributions from the kinetic and confinement energies. A perturbative analysis performed around the first magic-angle allows us to explore analytically the details of such an energy balance.