Supercurrent and quasiparticle interference between twod-wave superconductors coupled by a normal metal or insulator

Abstract

In the presence of an elastic barrier at both interfaces of a mesoscopic d-wave superconductor-normalmetal-d-wave superconductor ͑DND junction͒, the Josephson current at zero temperature is studied by using a simple matrix method. As a limiting case, the tunneling between two d-wave superconductors coupled by a insulator barrier ͑DID structure͒ is particularly addressed. The effects of sign change and anisotropic gap structure of the d x 2 Ϫy 2 superconductor are carefully considered in the Andreev reflection. The coupling of forward-moving quasiparticles and backward-moving quasiparticles with different pair potentials leads to contrasting Andreev spectra in different motion angle regions, which is specific to our model. Unlike conventional superconducting point-contact junctions, the conduction crossing the Fermi surface plays an important role in determining the critical current. Our theoritical results suggest that the dependence of the critical current on the grain boundary tilt angle provides a clue to identify the pairing symmetry of high-T c superconductors.

Grain boundaries in high-Tcsuperconductors

“…Pairing symmetry does not significantly affect the normal-state resistivity R n A of the interfaces. The high R n A values of typically 10 Ϫ8 ⍀ cm 2 , which correspond to resistivities of the order of 10 Ϫ1 ⍀ cm for an assumed effective thickness of a resistive region of ϳ1 nm (Chaudhari, Dimos, and Mannhart, 1990), are indicative 11 See, for example, Millis, 1994;Barash et al, 1995;Bruder et al, 1995;Deutscher and Maynard, 1995;Kashiwaya, 1995, 1996;Tang et al, 1996;Walker and Luettmer-Strathmann, 1996;Fogelströ m et al, 1997;Hurd, 1997;Fogelströ m and Yip, 1998;Lö fwander, Johansson, et al, 1998;Lö fwander, Shumeiko, and Wendin, 1998;Ö stlund, 1998;Golubov and Kupryianov, 1999;Hogan-O'Neill et al, 1999; FIG. 58.…”

Theory of novel properties of Josephson effect in anisotropic superconductors

“…4) is due to the difference of the temperature dependence of G p (ϕ) and G n (ϕ). The Josephson effect in d/I/N/I/d (d-wave superconductor/insulator/normal metal/insulator/d-wave superconductor) junctions was also studied recently [34,44,45]. The nonmonotonous temperature dependence of the maximum Josephson current is expected similar to the case of a d/I/d junction, where the length of the normal region is smaller than the coherence length in the normal region.…”

Self-consistent interface properties ofd- ands-wave superconductors

“…In the past few years there have been a number of microscopic calculations of surfaces and interfaces in superconducting systems with a d-wave order parameter. Most of the theoretical results have been obtained using tunnelling theory, or Andreev's approximation [5][6][7][8][9][10][11] in which the tunnelling barrier and the order parameter are not found self-consistently.…”