Room temperature local ferromagnetism and nanoscale domain growth in the ferromagnetic semiconductor GeFe

TL;DR

This study reveals that GeFe, a ferromagnetic semiconductor, exhibits room temperature local ferromagnetic domains and nanoscale domain growth, with strong Fe 3d and Ge 4p hybridization and a large orbital magnetic moment.

Contribution

First observation of nanoscale ferromagnetic domain growth in GeFe, demonstrating room temperature local ferromagnetism and detailed electronic structure analysis.

Findings

Local ferromagnetic domains exist at room temperature.

Nanoscale domain growth occurs as temperature decreases.

Fe 3d electrons strongly hybridize with Ge 4p states.

Abstract

We investigate the local electronic structure and magnetic properties of the group IV based ferromagnetic semiconductor, GeFe, using soft X ray magnetic circular dichroism. Our results show that the doped Fe 3d electrons are strongly hybridized with the Ge 4p states, and have an unusually large orbital magnetic moment relative to the spin magnetic moment; i.e., morb/mspin = 0.3. We find that local ferromagnetic domains, which are formed through ferromagnetic exchange interactions in the high Fe content regions of the GeFe films, exist at room temperature, well above the Curie temperature. We demonstrate the first observation of the intriguing nanoscale domain growth process in which ferromagnetic domains expand as the temperature decreases, followed by a transition of the entire film into a ferromagnetic state at the Curie temperature.