Epitaxial growth of the cubic L21-Mn2.6Ga Heusler alloy on MgO(001)

Abstract

The Mn3Ga Heusler alloy possesses different crystalline structures representing a range of properties of interest for spintronic applications. We report on the structural and magnetic characterization of the disordered cubic-fcc L21-Mn2.6Ga thin films grown on MgO(001) substrates. The first two nanometers of thickness of the Mn2.6Ga thin films are highly strained to the substrate with a lattice mismatch of 9.54%, playing the role of a template layer for the subsequent growth of relaxed L21-Mn2.6Ga. Once the films reach a critical thickness of 15 nm, the cubic phase reorients its epitaxial relationship from a (001) to a (111) in-plane orientation. Magnetic measurements show that the samples exhibit perpendicular magnetic anisotropy and also that the usually antiferromagnetic L21-Mn3Ga films are ferromagnetic with a Curie temperature >400 K due to partially compensated Mn moments.