Andreev edge state on semi-infinite triangular lattice: Detecting the pairing symmetry in

¹ Kavli Institute for Theoretical Physics, University of California Santa Barbara, CA 93106,USA
² Department of Physics and Astronomy, University of British Columbia Vancouver, B.C. V6T 1Z1, Canada
³ Physics Division, National Center for Theoretical Sciences - Hsinchu 300, Taiwan

Received: 12 October 2004
Accepted: 10 January 2005

Abstract

We study the Andreev edge state on the semi-infinite triangular lattice with different pairing symmetries and boundary topologies. We find a rich phase diagram of zero-energy Andreev edge states that is a unique fingerprint of each of the possible pairing symmetries. We propose to pin down the pairing symmetry in recently discovered _x material by the Fourier-transformed scanning tunneling spectroscopy for the edge state. A surprisingly rich phase diagram is found and explained by a general gauge argument and mapping to 1D tight-binding model. Extensions of this work are discussed at the end.