Spectroscopic Evidence for Strong Quantum Spin Fluctuations with Itinerant Character in YFe2Ge2

TL;DR

This study uses spectroscopic techniques to reveal strong, fluctuating quantum spin moments in YFe2Ge2, indicating significant spin fluctuations with itinerant character, similar to those in Fe-based superconductors, despite the absence of magnetic order.

Contribution

It provides the first spectroscopic evidence of large quantum spin fluctuations in YFe2Ge2, expanding the known chemical range of Fe-based superconducting-like magnetic signatures.

Findings

Large fluctuating spin moments observed on Fe sites

Exchange multiplets similar to Fe-pnictide superconductors

Implication of broader magnetic characteristic range in related compounds

Abstract

We report x-ray absorption and photoemission spectroscopy of the electronic structure in the normal state of metallic YFe2Ge2. The data reveal evidence for large fluctuating spin moments on the Fe sites, as indicated by exchange multiplets appearing in the Fe 3s core level photoemission spectra, even though the compound does not show magnetic order. The magnitude of the multiplet splitting is comparable to that observed in the normal state of the Fe-pnictide superconductors. This shows a connection between YFe2Ge2 and the Fe-based superconductors even though it contains neither pnictogens nor chalcogens. The implication is that the chemical range of compounds showing at least one of the characteristic magnetic signatures of the Fe-based superconductors is broader than previously thought.