Tuning emergent magnetism in a Hund's impurity

TL;DR

This paper demonstrates experimental control over a single magnetic impurity to explore and tune emergent magnetism and Kondo physics, providing insights into Hund's metals and strongly correlated electron systems.

Contribution

It introduces a method to tune a Hund's impurity via hydrogenation and STM techniques, bridging experimental control with many-body theoretical models.

Findings

Controlled transition from magnetic moments to Kondo state

Experimental tuning of magnetic anisotropy and hybridization

Comparison with advanced many-body theories

Abstract

The recently proposed theoretical concept of a Hund's metal is regarded as a key to explain the exotic magnetic and electronic behavior occuring in the strongly correlated electron systems of multiorbital metallic materials. However, a tuning of the abundance of parameters, that determine these systems, is experimentally challenging. Here, we investigate the smallest possible realization of a Hund's metal, a Hund's impurity, realized by a single magnetic impurity strongly hybridized to a metallic substrate. We experimentally control all relevant parameters including magnetic anisotropy and hybridization by hydrogenation with the tip of a scanning tunneling microscope and thereby tune it through a regime from emergent magnetic moments into a multi-orbital Kondo state. Our comparison of the measured temperature and magnetic field dependent spectral functions to advanced many-body theories will give relevant input for their application to non-Fermi liquid transport, complex magnetic order, or unconventional superconductivity.