title: Unified Theory of PT and CP Invariant Topological Metals and Nodal Superconductors.
abstract: As PT and CP symmetries are fundamental in physics, we establish a unified topological theory of PT and CP invariant metals and nodal superconductors, based on the mathematically rigorous KO theory. Representative models are constructed for all nontrivial topological cases in dimensions d=1, 2, and 3, with their exotic physical meanings being elucidated in detail. Intriguingly, it is found that the topological charges of Fermi surfaces in the bulk determine an exotic direction-dependent distribution of topological subgap modes on the boundaries. Furthermore, by constructing an exact bulk-boundary correspondence, we show that the topological Fermi points of the PT and CP invariant classes can appear as gapless modes on the boundary of topological insulators with a certain type of anisotropic crystalline symmetry.
authors.affiliation: Max-Planck-Institute for Solid State Research, D-70569 Stuttgart, Germany.|Department of Physics and Center of Theoretical and Computational Physics, The University of Hong Kong, Pokfulam Road, Hong Kong, China.
authors.forename: Y X
authors.initials: YX
authors.lastname: Zhao
authors.affiliation: Max-Planck-Institute for Solid State Research, D-70569 Stuttgart, Germany.
authors.forename: Andreas P
authors.initials: AP
authors.lastname: Schnyder
authors.affiliation: Department of Physics and Center of Theoretical and Computational Physics, The University of Hong Kong, Pokfulam Road, Hong Kong, China.
authors.forename: Z D
authors.initials: ZD
authors.lastname: Wang