Spin-Orbit Scattering and Pair Breaking in a Structurally Disordered Copper-Oxide Layer

TL;DR

This paper investigates how spin-orbit scattering caused by oxygen displacements affects electron scattering and pair-breaking in disordered copper-oxide layers, with implications for superconductivity suppression in certain structural phases.

Contribution

It reveals that spin fluctuations do not enhance spin-orbit scattering and shows that spin-orbit scattering can strongly break pairs in disordered cuprate superconductors.

Findings

Spin fluctuations do not enhance spin-orbit scattering due to time-reversal symmetry.

Spin-orbit scattering can cause significant pair-breaking in disordered cuprates.

Structural disorder influences superconductivity suppression in cuprate systems.

Abstract

To leading order in displacement size, the scattering of electrons in a Cu-O plane from O displacements perpendicular to that plane is due to spin-orbit coupling. This scattering is investigated with the following results: (1) As a consequence of time-reversal symmetry, spin fluctuations, which can strongly enhance scattering from a spin impurity, do not enhance spin-orbit scattering; and (2) for a superconductor with a $d_{x^2-y^2}$ gap function, pair-breaking from spin-orbit scattering can be strong, particularly in a structurally disordered phase in which locally CuO$_6$ octahedra tilt as in the orthorhombic phase of La$_2$CuO$_4$, but globally the average structure is tetragonal. These results are discussed in the context of the (La,Nd)-(Sr,Ba)-Cu-O system where certain structural transitions are observed to suppress superconductivity.