Visualization of local magnetic moments emerging from impurities in the Hund's metal states of FeSe

TL;DR

This study uses scanning tunneling microscopy to investigate how impurities induce local magnetic moments in FeSe, shedding light on its magnetic properties near a quantum critical point relevant to high-temperature superconductivity.

Contribution

It provides direct experimental evidence of impurity-induced local magnetic moments in FeSe, advancing understanding of its magnetic quantum criticality and superconducting behavior.

Findings

Impurities induce local magnetic moments in FeSe.

Magnetic moments develop near the quantum critical point.

Insights into magnetic ordering in FeSe from impurity effects.

Abstract

Understanding the origin of the magnetism of high temperature superconductors is crucial for establishing their unconventional pairing mechanism. Recently, theory predicts that FeSe is close to a magnetic quantum critical point, and thus weak perturbations such as impurities could induce local magnetic moments. To elucidate such quantum instability, we have employed scanning tunneling microscopy and spectroscopy. In particular, we have grown FeSe film on superconducting Pb(111) using molecular beam epitaxy and investigated magnetic excitation caused by impurities in the proximity-induced superconducting gap of FeSe. Our study provides a deep insight into the origin of the magnetic ordering of FeSe by showing the way local magnetic moments develop in response to impurities near the magnetic quantum critical point.