Pressure induced renormalization of energy scales in the unconventional superconductor FeTe0.6Se0.4

TL;DR

This study investigates how applying pressure up to 1.5 GPa affects the energy scales in the unconventional superconductor FeTe0.6Se0.4, revealing a complex relationship between resonance energy and transition temperature linked to hybridization and pairing strength.

Contribution

It provides the first detailed pressure-dependent analysis of neutron spin resonance and Tc in FeTe0.6Se0.4, highlighting the non-linear scaling and renormalization effects.

Findings

Resonance energy and Tc both increase with pressure up to ~1.3 GPa.

Resonance energy does not scale linearly with Tc, indicating complex interactions.

Pressure appears to weaken the pairing mechanism in the superconductor.

Abstract

We have carried out a pressure study of the unconventional superconductor FeTe0.6Se0.4 up to 1.5 GPa by neutron scattering, resistivity and magnetic susceptibility measurements. We have extracted the neutron spin resonance energy and the superconducting transition temperature as a function of applied pressure. Both increase with pressure up to a maximum at ~1.3 GPa. This analogous qualitative behavior is evidence for a correlation between these two fundamental parameters of unconventional superconductivity. However, Tc and the resonance energy do not scale linearly and thus a simple relationship between these energies does not exist even in a single sample. The renormalization of the resonance energy relative to the transition temperature is here attributed to an increased hybridization. The present results appear to be consistent with a pressure-induced weakening of the coupling strength associated with the fundamental pairing mechanism.