Probing spin correlations using angle resolved photoemission in a coupled metallic/Mott insulator system

TL;DR

This study reveals how angle resolved photoemission can probe spin correlations in a layered system combining metallic and Mott insulating states, showing that photoemission can reflect the magnetic properties of correlated electrons.

Contribution

It demonstrates that photoemission spectra can reveal spin correlations in a coupled metallic/Mott insulator system, supported by a Kondo lattice model analysis.

Findings

Sharp band-like features observed in the Mott layer's spectral function.

Hole propagation retains memory of the Mott layer's magnetism.

Photoemission can serve as a non-magnetic probe of spin susceptibility.

Abstract

A nearly free electron metal and a Mott insulating state can be thought of as opposite ends of possibilities for the motion of electrons in a solid. In the magnetic oxide metal PdCrO$_{2}$, these two coexist as alternating layers. Using angle resolved photoemission, we surprisingly find sharp band-like features in the one-electron removal spectral function of the correlated subsystem. We show that these arise because a hole created in the Mott layer moves to and propagates in the metallic layer while retaining memory of the Mott layer's magnetism. This picture is quantitatively supported by a strong coupling analysis capturing the physics of PdCrO$_{2}$ in terms of a Kondo lattice Hamiltonian. Our findings open new routes to use the non-magnetic probe of photoemission to gain insights into the spin-susceptibility of correlated electron systems.