Oxygen vacancies controlled multiple magnetic phases in epitaxial single crystal Co0.5 (Mg0.55 Zn0.45)0.5 O 1-v thin films

Abstract

High quality single-crystal fcc-Cox (Mgy Zn1-y)1-x O1-v epitaxial thin films with high Co concentration up to x = 0.5 have been fabricated by molecular beam epitaxy. Systematic magnetic property characterization and soft X-ray absorption spectroscopy analysis indicate that the coexistence of ferromagnetic regions, superparamagnetic clusters, and non-magnetic boundaries in the as-prepared Co x (Mgy Zn1-y)1-x O1-v films is a consequence of the intrinsic inhomogeneous distribution of oxygen vacancies. Furthermore, the relative strength of multiple phases could be modulated by controlling the oxygen partial pressure during sample preparation. Armed with both controllable magnetic properties and tunable band-gap, Cox (Mgy Zn1-y)1-x O1-v films may have promising applications in future spintronics.