A Triplet Resonance in Superconducting FeSe0.4Te0.6

TL;DR

This paper demonstrates that the spin resonance in optimally doped Fe(Se,Te) splits into three peaks under high magnetic field, indicating a two-particle triplet bound state and highlighting the role of magnetic fluctuations in superconductivity.

Contribution

It provides experimental evidence of triplet bound states in Fe(Se,Te) superconductors using high-field inelastic neutron scattering.

Findings

Spin resonance splits into three peaks in high magnetic field.

Evidence supports a two-particle triplet bound state.

Magnetic fluctuations are crucial in superconductivity.

Abstract

From heavy fermions to cuprates and iron pnictides, a spin resonance is a staple of nearly magnetic superconductors. Possible explanations include a two-particle bound state or loss of magnon damping in the superconductor. While both scenarios suggest a central role for magnetic fluctuations, distinguishing them is important to identify the right theoretical framework and to guide the search for higher temperature superconductors. Using inelastic neutron scattering technique, we show that the spin resonance in optimally doped Fe(Se,Te) splits into three peaks in a high magnetic field, a signature of a two-particle triplet bound state