Magnetic fluctuations in pair density wave superconductors

TL;DR

This paper investigates the magnetic properties of pair density wave superconductors, revealing distinctive spin excitation features that differ from conventional d-wave superconductors, aligning with recent experimental observations.

Contribution

It provides the first theoretical calculation of magnetic susceptibility in pair density wave states, highlighting unique spin excitation signatures.

Findings

No spin-gap in the pair density wave phase

Absence of a magnetic resonance peak

Consistent with recent neutron scattering experiments

Abstract

Pair density wave superconductivity constitutes a novel electronic condensate proposed to be realized in certain unconventional superconductors. Establishing its potential existence is important for our fundamental understanding of superconductivity in correlated materials. Here we compute the dynamical magnetic susceptibility in the presence of a pair density wave ordered state, and study its fingerprints on the spin-wave spectrum including the neutron resonance. In contrast to the standard case of d-wave superconductivity, we show that the pair density wave phase exhibits neither a spin-gap nor a magnetic resonance peak, in agreement with a recent neutron scattering experiment on underdoped La$_{1.905}$Ba$_{0.095}$CuO$_4$ [Z. Xu et al., Phys. Rev. Lett. 113, 177002 (2014)].