Epitaxial growth of Mn5Ge3/Ge(111) heterostructures for spin injection

Abstract Epitaxial Mn 5 Ge 3 /Ge(111) heterostructures were grown by Solid Phase Epitaxy (SPE) method, which consists of a room temperature Mn deposition followed by thermal annealing. It is shown that upon annealing at a temperature of about ~ 430–450  °C, the Mn 5 Ge 3 phase is formed and it is stable up to ~ 850  °C. This phase is the unique epitaxial phase observed on the Ge(111) substrate. Transmission electron diffraction (TED) patterns confirm that the hexagonal basal (001) plan of Mn 5 Ge 3 is parallel to the (111) plan of the Ge substrate and cross-sectional transmission electronic microscopy (TEM) analyses reveal a relatively smooth interface at the atomic scale. Magnetic characterizations indicate that epitaxial Mn 5 Ge 3 films present a strong ferromagnetism up to room temperature. However, in contrast to bulk Mn 5 Ge 3 material which has uniaxial anisotropy along the c axis, epitaxial Mn 5 Ge 3 films exhibit easy axis of magnetization lying in the hexagonal basal (001) plane, parallel to the interface between the Mn 5 Ge 3 films and the substrate.