Hall effect characterization of electronic transition behind the metamagnetic transition in FeRh

TL;DR

This study uses Hall and magnetoresistance measurements to investigate the electronic changes during the metamagnetic transition in FeRh, revealing a significant carrier density suppression linked to an orbital selective Mott transition.

Contribution

It provides new insights into the electronic mechanism behind the metamagnetic transition in FeRh, highlighting the role of Fe/Rh substitution defects and an orbital selective Mott transition.

Findings

Carrier density drops by at least an order of magnitude during transition

Intrinsic doping from Fe/Rh substitution defects affects electronic properties

Orbital selective Mott transition likely drives the metamagnetic transition

Abstract

The antiferromagnetic ground state and the metamagnetic transition to the ferromagnetic state of CsCl-ordered FeRh epilayers have been characterized using Hall and magnetoresistance measure- ments. On cooling into the ground state, the metamagnetic transition is found to coincide with a suppression in carrier density of at least an order of magnitude below the typical metallic level shown by the ferromagnetic state. The data reveal that this sub-metallic density of electron-like majority carriers in the antiferromagnetic phase are attributable to intrinsic doping from Fe/Rh substitution defects, with approximately two electrons per pair of atoms swapped. Based on these observations it is suggested that an orbital selective Mott transition, selective to the Fe 3d electrons drives the metamagnetic transition.