Germanium-Based Ferromagnetic Semiconductor Ge1-xFex for Silicon Spintronics

Abstract

Ferromagnetic semiconductor Ge1-xFex thin films were grown on Si(001) substrates by low-temperature molecular beam epitaxy. The crystal structure of the Ge1-xFex films was of diamond type for 0 {less than or equal to} x {less than or equal to} 17.5%. Magnetic circular dichroism (MCD) characterizations revealed that the origin of the ferromagnetic ordering in the Ge1-xFex films comes only from the diamond lattice phase with the cooperation of s,p-d exchange interactions. The Ge1-xFex films clearly exhibited the anomalous Hall effect at lower temperatures, and their ferromagnetic behavior was consistent with the results of the MCD observations. As the Fe content increased, the resistivity of the film monotonically decreased and simultaneously the Curie temperature monotonically increased. All the experimental results indicate that the Ge1-xFex films grown on Si(001) have the properties of intrinsic ferromagnetic semiconductor.