Magneto-optical properties of a new group-IV ferromagnetic semiconductor Ge1-xFex grown by low-temperature molecular beam epitaxy

TL;DR

This study reports the successful growth and characterization of a new ferromagnetic semiconductor, Ge1-xFex, demonstrating intrinsic ferromagnetism with properties tunable by Fe content and growth temperature.

Contribution

It is the first demonstration of intrinsic ferromagnetism in Ge1-xFex grown by low-temperature MBE without precipitates, revealing s,p-d exchange interactions.

Findings

Ferromagnetism increases linearly with Fe content

Band structure remains similar to bulk Ge

Large spin splitting induced by Fe incorporation

Abstract

A new group-IV ferromagnetic semiconductor, Ge1-xFex, was successfully grown by low-temperature molecular beam epitaxy (LT-MBE) without precipitation of ferromagnetic Ge-Fe intermetallic compounds. The ferromagnetism of Ge1-xFex films was investigated by magnetic circular dichroism (MCD). In particular, the influence of the Fe content (FFe/FGe =1 - 10%) and growth temperature (100, 200OC) on the ferromagnetism was carefully studied. The MCD measurements revealed that the band structure of the Ge1-xFex films was identical with that of bulk Ge, and that the large spin splitting of the band structure was induced by the incorporation of Fe atoms into the Ge matrix, indicating the existence of s,p-d exchange interactions. The Ge1-xFex films showed ferromagnetic behavior and the ferromagnetic transition temperature linearly increased with increasing the Fe composition. These results indicate that the epitaxially grown Ge1-xFex is an intrinsic ferromagnetic semiconductor.