# Shapiro Steps as a Direct Probe of $pm s$-wave Symmetry in Multi-gap Superconducting Josephson Junctions - Condensed Matter > Superconductivity

Shapiro Steps as a Direct Probe of $pm s$-wave Symmetry in Multi-gap Superconducting Josephson Junctions - Condensed Matter > Superconductivity - Download this document for free, or read online. Document in PDF available to download.

Abstract: We theoretically study the Shapiro steps in a hetero Josephson junction madeof a single-gap superconductor and a two-gap one. We find that an anomalous DCJosephson current is induced by tuning the frequency of an applied microwave tothe Josephson-Leggett mode frequency, which creates an extra step structure inthe $I$-$V$ characteristics besides the conventional Shapiro steps. The stepheights at the resonance voltages exhibit an alternate structure of a large andsmall value reflecting the gap symmetry of the two-gap superconductor. In the\$\pm s-wave case in which the two gaps have opposite signs in the two-gapsuperconductor the steps with odd index are enhanced, whereas in the s-wavecase the ones with even index have larger values. The existence of thefractional Shapiro steps is also predicted.

Author: Yukihiro Ota, Masahiko Machida, Tomio Koyama

Source: https://arxiv.org/