Topological origin of zero-energy edge states in particle-hole symmetric systems.
A criterion to determine the existence of zero-energy edge states is discussed for a class of particle-hole symmetric Hamiltonians. A "loop" in a parameter space is assigned for each one-dimensional bulk Hamiltonian, and its topological properties, combined with the chiral symmetry, play an essential role. It provides a unified framework to discuss zero-energy edge modes for several systems such as fully gapped superconductors, two-dimensional d-wave superconductors, and graphite ribbons. A variance of the Peierls instability caused by the presence of edges is also discussed.
Ryu
Shinsei
S
Department of Applied Physics, University of Tokyo, 7-3-1 Hongo Bunkyo-ku, Japan.
Hatsugai
Yasuhiro
Y