Orbital-active Dirac materials from the symmetry principle Academic Article uri icon

abstract

  • AbstractDirac materials, starting with graphene, have drawn tremendous research interest in the past decade. Instead of focusing on the $p_{z}$ p z orbital as in graphene, we move a step further and study orbital-active Dirac materials, where the orbital degrees of freedom transform as a two-dimensional irreducible representation of the lattice point group. Examples of orbital-active Dirac materials occur in a broad class of systems, including transition-metal-oxide heterostructures, transition-metal dichalcogenide monolayers, germanene, stanene, and optical lattices. Different systems are unified based on symmetry principles. The band structure of orbital-active Dirac materials features Dirac cones at $K(K')$ K ( K ) and quadratic band touching points at , regardless of the origin of the orbital degrees of freedom. In the strong anisotropy limit, i.e., when the -bonding can be neglected, flat bands appear due to the destructive interference. These features make orbital-active Dirac materials an even wider playground for searching for exotic states of matter, such as the Dirac semi-metal, ferromagnetism, Wigner crystallization, quantum spin Hall state, and quantum anomalous Hall state.

published proceedings

  • Quantum Frontiers

altmetric score

  • 1.25

author list (cited authors)

  • Xu, S., & Wu, C.

citation count

  • 2

complete list of authors

  • Xu, Shenglong||Wu, Congjun