Spin polarization and electronic structure of ferromagnetic Mn5Ge3 epilayers

Germanium‐based alloys hold great promise for future spintronics applications, due to their potential for integration with conventional Si‐based electronics. High‐quality single phase Mn5Ge3(0001) films, grown by solid‐phase epitaxy on Ge(111) and GaAs(111), exhibit strong ferromagnetism up to the Curie temperature TC ∼ 296 K. Point Contact Andreev Reflection (PCAR) measurements on Mn5Ge3 epilayers reveal a spin‐polarization P = 42 ± 5% for both substrates. We also calculate the spin polarization of bulk Mn5Ge3 in the diffusive and ballistic regimes using density‐functional theory (DFT). The measured spin polarization exceeds the theoretical estimates of PDFT = 35 ± 5% and 10 ± 5% for the diffusive and ballistic limits, respectively. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)