$p$-wave superconductivity and Josephson current in $p$-wave unconventional magnet/$s$-wave superconductor hybrid systems

TL;DR

This paper investigates the emergence of $p$-wave superconductivity and Josephson effects in hybrid systems combining $p$-wave unconventional magnets with $s$-wave superconductors, revealing zero-energy flat bands and tunable Josephson currents.

Contribution

It demonstrates the formation of $s+p$-wave-like superconducting states and analyzes the Josephson current behavior influenced by zero-energy flat bands and temperature.

Findings

Zero-energy flat bands emerge at the edge due to noncollinear spin structure.

Odd-frequency spin-triplet pairing is induced at the edge.

Josephson current exhibits first harmonic coupling influenced by the magnetic order.

Abstract

We study the surface density of states in $p$-wave unconventional magnet-spin-singlet $s$-wave superconductor hybrid systems ($p$-wave unconventional magnetic superconductors). Owing to the noncollinear spin structure in $p$-wave unconventional magnets, the spin-singlet $s$-wave pair potential behaves as the spin-triplet $p$-wave superconductivity. As a result, zero-energy flat bands can emerge at the edge. Analyzing the pair amplitude at the edge, odd-frequency spin-triplet even-parity pairing is induced in the presence of zero-energy flat bands, while even-frequency spin-singlet even-parity remains. We also demonstrate the Josephson current in superconducting junctions with $p$-wave unconventional magnet-spin-singlet $s$-wave superconductor hybrid systems. By the cooperation of spin-singlet $s$-wave pair potential and the $p$-wave unconventional magnetic order, the coupling of the spin-singlet even-parity pairings in junctions generates the first harmonics of the Josephson current. In addition, the temperature dependence of the maximum Josephson current can be tuned by the chemical potential, which determines the generation of zero-energy flat bands. Our results indicate that $s+p$-wave-like superconducting state is generated in $p$-wave unconventional magnet-$s$-wave superconductor hybrid systems.