Resonance mode in $B_{1g}$ Raman scattering -- a way to distinguish between spin-fluctuation and phonon-mediated $d-$wave superconductivity

TL;DR

This paper proposes that $B_{1g}$ Raman scattering can differentiate between phonon-mediated and spin-fluctuation-mediated $d$-wave superconductivity by observing the presence or absence of a resonance at a specific frequency.

Contribution

It introduces a method to distinguish superconducting pairing mechanisms using Raman scattering resonance features in $B_{1g}$ symmetry.

Findings

Resonance at $\, ext{ω}_{res} < 2 ext{Δ}_{max}$ indicates spin-fluctuation pairing.

No resonance develops in phonon-mediated $d$-wave superconductors.

The approach parallels neutron resonance phenomena.

Abstract

We argue that Raman scattering in $B_{1g}$ symmetry allows one to distinguish between phonon-mediated and magnetically-mediated $d-$wave superconductivity. In spin mediated superconductors, $B_{1g}$ Raman intensity develops a resonance at a frequency $\omega_{res} < 2\Delta_{max}$, whose origin is similar to a neutron resonance. In phonon-mediated $d-$wave superconductors, such a resonance does not develop. Several extensions of the argument are presented.