On edge states in superconductors with time inversion symmetry breaking

Superconducting states with different internal topology are discussed for the layered high-T-c materials. If the time inversion symmetry is broken, the superconductivity is determined not only by the symmetry of the superconducting state but also by the topology of the ground state. The latter is determined by the integer-valued momentum-space topological invariant N. The current carrying boundary between domains with different N (N-2 not equal N-1) is considered. The current is produced by fermion zero modes, the number of which per layer is 2(N-2-N-1). (C) 1997 American Institute of Physics. [S0021-3640(97)00919-5].