Spin polarization of Fe4N thin films determined by point-contact Andreev reflection

Abstract

The spin polarization of (100)-oriented γ′-Fe4N layers grown on MgO(001) substrates by molecular beam epitaxy was deduced from point contact Andreev reflection measurements, and the value was compared with that of α-Fe. The spin polarization (P) for γ′-Fe4N is approximately 0.59 at 7.8 K. This value is distinctly larger than that for α-Fe (P=0.49 at 7.8 K) measured with an identical setting. The mechanism of enhanced spin polarization in γ′-Fe4N is discussed.