Anomalous Hall effect at the spontaneously electron-doped polar surface of PdCoO2 ultrathin films

TL;DR

This study demonstrates the emergence of an anomalous Hall effect driven by surface ferromagnetic states in ultrathin PdCoO2 films, revealing new spin-related phenomena at nonmagnetic metal surfaces due to electronic reconstruction.

Contribution

It uncovers the surface-induced ferromagnetic states and their role in anomalous Hall effects in PdCoO2 ultrathin films, a novel finding in nonmagnetic metals.

Findings

Detection of surface-magnetization-driven anomalous Hall effect.

Thickness- and termination-dependent measurements confirm surface origin.

Discussion of unconventional Hall resistance due to electron doping.

Abstract

We revealed the electrical transport through surface ferromagnetic states of a nonmagnetic metal PdCoO2. Electronic reconstruction at the Pd-terminated surface of PdCoO2 induces Stoner-like ferromagnetic states, which could lead to spin-related phenomena among the highly conducting electrons in PdCoO2. Fabricating a series of nanometer-thick PdCoO2 thin films, we detected a surface-magnetization-driven anomalous Hall effect via systematic thickness- and termination-dependent measurements. Besides, we discuss that finite magnetic moments in electron doped CoO2 triangular lattices may have given rise to additional unconventional Hall resistance.