Soft X-ray spectroscopy study of Fe impurities in Mn3-xCoxGa Heusler films

Abstract

Co-substituted Mn3-xCoxGa Heusler films, exhibiting the magnetic anisotropy transition with x, are considered as promising spintronic materials. We have investigated the local electronic structures of Mn3-xCoxGa films as well as the chemical distributions of the substituted ions employing photoemission spectroscopy (PES), scanning photoelectron microscopy (SPEM), soft X-ray absorption spectroscopy (XAS), and soft X-ray magnetic circular dichroism (XMCD). SPEM measurements show that Co ions are distributed homogeneously in Mn3-xCoxGa films. On the other hand, some Fe impurities are detected in the capping layers of Mn3-xCoxGa films. Despite the existence of ferromagnetic metallic Fe impurities, however, it is found that the magnetic anisotropy transition in Mn3-xCoxGa is determined mainly by the substituted Co ions but hardly by Fe impurities. This work demonstrates that, in searching for new functional materials, special attention should be paid on the magnetic Fe impurities that might affect their magnetic properties.