Influence of impurity-scattering on tunneling conductance in d-wave superconductors with broken time reversal symmetry

• Published in: Journal of the Physical Society of Japan 2003-07, Vol.72 (7), p.1718-1723
• Main Authors: KITAURA, Naoki, ITOH, Hiroyoshi, ASANO, Yasuhiro, TANAKA, Yukio, INOUE, Jun-Ichiro, TANUMA, Yasunari, KASHIWAYA, Satoshi
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Physics; Proximity effects, weak links, tunneling phenomena, and Josephson effects; Proximity effects, weak links, tunneling phenomena, and josephson effects, adreev effect, sn and sns junctions; Superconductivity
• ISSN: 0031-9015; 1347-4073
• DOI: 10.1143/jpsj.72.1718

Effects of impurity scattering on tunneling conductance in dirty normal-metal/insulator/superconductor junctions are studied based on the Kubo formula and the recursive Green function method. The zero-bias conductance peak (ZBCP) is a consequence of the unconventional pairing symmetry in superconductors. The impurity scattering in normal metals suppresses the amplitude of the ZBCP. The degree of the suppression agrees well with results of the quasiclassical Green function theory. When superconductors have d+is-wave pairing symmetry, the time-reversal symmetry is broken in superconductors and the ZBCP splits into two peaks. The random impurity scattering reduces the height of the two splitting peaks. The position of the splitting peaks, however, almost remains unchanged even in the presence of the strong impurity scattering. Thus the two splitting peaks never merge into a single ZBCP.