<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="italic">c</mi></math>-axis Josephson Tunneling between <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>YBa</mi></mrow><mrow><mn>2</mn></mrow></msub></mrow><mrow><msub><mrow><mi>Cu</mi></mrow><mrow><mn>3</mn></mrow></msub></mrow><mrow><msub><mrow><mi>O</mi></mrow><mrow><mn>7</mn><mo>−</mo><mi>δ</mi></mrow></msub></mrow></math> and Pb: Direct Evidence for Mixed Order Parameter Symmetry in a High- <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>T</mi></mrow><mrow><mi>c</mi></mrow></msub></mrow></math> Superconductor

K. A. Kouznetsov; A. G. Sun; B. Chen; A. S. Katz; S. R. Bahcall; John Clarke; R. C. Dynes; D. A. Gajewski; S. H. Han; M. B. Maple; J. Giapintzakis; J.-T. Kim; D. M. Ginsberg

doi:10.1103/PhysRevLett.79.3050

$c$ -axis Josephson Tunneling between ${YBa}_{2} {Cu}_{3} O_{7 - δ}$ and Pb: Direct Evidence for Mixed Order Parameter Symmetry in a High- $T_{c}$ Superconductor

K. A. Kouznetsov, A. G. Sun, B. Chen, A. S. Katz, S. R. Bahcall, John Clarke, R. C. Dynes, D. A. Gajewski, S. H. Han, M. B. Maple, J. Giapintzakis, J.-T. Kim, and D. M. Ginsberg

Phys. Rev. Lett. 79, 3050 – Published 20 October 1997

Abstract

We report a new class of $c$ -axis Josephson tunneling experiments in which a conventional superconductor (Pb) is deposited across a single twin boundary of a $YBa_{2} {Cu}_{3} O_{7 - δ}$ (YBCO) crystal. We measure the critical current as a function of the magnitude and angle of a magnetic field applied in the plane of the junction. In all samples, we observe a clear experimental signature of an order parameter phase shift across the twin boundary. These results provide strong evidence for mixed $d$ - and $s$ -wave pairing in YBCO, with a reversal in the sign of the $s$ -wave component across the twin boundary.

Received 23 May 1997

DOI:https://doi.org/10.1103/PhysRevLett.79.3050

Authors & Affiliations

K. A. Kouznetsov^1,2, A. G. Sun³, B. Chen^1,2, A. S. Katz³, S. R. Bahcall^1,2, John Clarke^1,2, R. C. Dynes³, D. A. Gajewski³, S. H. Han³, M. B. Maple³, J. Giapintzakis⁴, J.-T. Kim⁴, and D. M. Ginsberg⁴

¹Department of Physics, University of California, Berkeley, California 94720,
²and Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720
³Department of Physics, University of California, San Diego, La Jolla, California 92093
⁴Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801