Epitaxial Growth Of Mn_5ge_3/ge(111) Heterostructures For Spin Injection

摘要

Epitaxial Mn_5Ge_3/Ge(ll1) 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 ℃, the Mn_5Ge_3 phase is formed and it is stable up to ～850 ℃. 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_5Ge_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_5Ge_3 films present a strong ferromagnetism up to room temperature. However, in contrast to bulk Mn_5Ge_3 material which has uniaxial anisotropy along the c axis, epitaxial Mn_5Ge_3 films exhibit easy axis of magnetization lying in the hexagonal basal (001) plane, parallel to the interface between the Mn_5Ge_3 films and the substrate.