Spin-triplet pairing and spin supercurrent in p-wave magnetic superconductors

Abstract

Spin-triplet superconductors are promising platforms for dissipationless spin transport, which typically originates from the interplay of ferromagnetism and superconductivity. However, ferromagnetism, in turn, suppresses superconductivity. As a class of unconventional magnetic materials, p-wave magnets possess the advantage of odd-parity spin splitting without net magnetism. Here we demonstrate through site-resolved spin-polarized band analysis that p-wave magnets exhibit nonzero in-plane spin polarization, which is crucial for spin-triplet correlations. We then investigate the p-wave magnetic superconductor composed of a p-wave magnet/s-wave superconductor hybrid system and calculate the site-resolved equal-spin component of anomalous Green's function, revealing the existence of equal-spin (spin-triplet) Cooper pairs. Next, we construct a normal metal/p-wave magnetic superconductor junction and calculate the equal-spin Andreev reflection coefficient using the nonequilibrium Green's function method. The results show that the equal-spin Andreev reflection coefficient is indeed nonzero, owing to the spin-triplet superconductivity. Finally, we construct a Josephson junction based on p-wave magnetic superconductors, study the spin Josephson effect, and identify the emergence of a spin superconducting diode effect.

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