Tunneling conductance in superconducting junctions with $p$-wave unconventional magnets breaking time-reversal symmetry

TL;DR

This paper investigates the tunneling conductance in junctions involving $p$-wave unconventional magnets that break time-reversal symmetry, revealing asymmetric conductance behavior and spin-dependent effects due to momentum-dependent spin splitting.

Contribution

It introduces a new model for $p$-wave unconventional magnets with time-reversal symmetry breaking and analyzes their tunneling conductance in superconductor junctions, extending prior simplified Hamiltonian approaches.

Findings

Asymmetric tunneling conductance with bias voltage in helical $p$-wave superconductor junctions.

Spin-resolved conductance differs for spin sectors due to time-reversal symmetry breaking.

Qualitative agreement with previous simplified Hamiltonian results.

Abstract

A new type of magnet called $p$-wave unconventional magnet is proposed, stimulated by the discovery of altermagnet. We study the tunneling conductance of $p$-wave unconventional magnet/superconductor junctions by adopting the effective Hamiltonian of $p$-wave unconventional magnets with time-reversal symmetry breaking, suggested in Ref [arXiv: 2309.01607 (2024)]. The tunneling conductance shows an asymmetric behavior with respect to bias voltage in the helical $p$-wave superconductor junctions. It is caused by the missing of helical edge states contributing to the charge conductance owing to the momentum-dependent spin-split feature of the Fermi surface in $p$-wave unconventional magnets. In chiral $d$ and $p$-wave superconductor junctions, the resulting spin-resolved tunneling conductance takes a different value for spin sectors due to the time-reversal symmetry breaking in superconductors. Our results qualitatively reproduce the results based on the simplified Hamiltonian in Ref [J.\ Phys.\ Soc.\ Jpn.\ \textbf{93}, 114703 (2024)], where only the odd function of the exchange coupling of $p$-wave unconventional magnets is taken into account, which gives the shift of the Fermi surface and preserves the time-reversal symmetry similar to the spin-orbit coupling.