Residual spin susceptibility in the spin-triplet, orbital-singlet model

TL;DR

This paper investigates how spin orbit coupling affects the spin susceptibility and Knight shift in spin-triplet, orbital-singlet superconductors, revealing a persistent residual susceptibility at low temperatures.

Contribution

It introduces a detailed analysis of spin orbit effects on multi-orbital spin-triplet superconductors with orbital-singlet character, contrasting them with single-band models.

Findings

Residual spin susceptibility persists at low temperatures.

Spin orbit coupling significantly influences Knight shift responses.

Differences identified between multi-orbital and single-band superconductors.

Abstract

Nuclear magnetic resonance (NMR) and Knight shift measurements are critical tools in the identification of spin-triplet superconductors. We discuss the effects of spin orbit coupling on the Knight shift and susceptibilities for a variety of spin triplet multi-orbital gap functions with orbital-singlet character and compare their responses to "traditional" single band spin-triplet ($p_x+ip_y$) superconductors. We observe a non-negligible residual spin-susceptibility at low temperature.