Spin-Orbit Ordering, Momentum Space Coexistence, and Cuprate Superconductivity

TL;DR

This paper proposes momentum-space coexistence of spin-orbit orders in cuprates, where specific spin orderings enhance interactions leading to d-wave superconductivity, predicting anisotropic spin susceptibility.

Contribution

It introduces a novel momentum-space coexistence of spin-orbit orders that promote superconductivity in cuprates, emphasizing the role of spin fluctuations and anisotropic susceptibility.

Findings

Spin-orbit orderings vary over the Fermi surface.

d_{xy} spin fluctuations induce d_{x^2-y^2} pairing.

Prediction of anisotropic spin susceptibility.

Abstract

Motivated by the energetic advantage of achieving coherent enhancement of effective spin-dependent interactions through approximate nesting, we propose specific forms of spin ordering, whose form varies over the Fermi surface, for the cuprate superconductors. Competing "spin-orbit" orderings involving order parameters in spatial $d_{x^2-y^2}$ and $d_{xy}$ waves at commensurate and incommensurate wavevectors, phase separated in momentum space, support behavior suggestive of observed phenomena. The $d_{xy}$ spin-orbit fluctuation induces an effective interaction that favors $d_{x^2-y^2}$-wave pairing, as required for the observed superconductivity. Anisotropic spin susceptibility is a crucial prediction of our mechanism.