INVESTIGATIONS ON EXCHANGE BIAS EFFECT IN MBE-GROWN TRANSITION-METAL CHALCOGENIDE CRTE THIN FILMS

Abstract

The thesis presents the study on exchange bias (EB) effects in several important Cr-Te compounds grown by molecular beam epitaxy (MBE). Firstly, zinc-blende CrTe/MnTe bilayer, which is predicted to be a promising exchange-biased structure with half-metallic interface, is obtained by epitaxial growth. Then the EB effects are systematically investigated as a function of temperature, cooling field and antiferromagnet (AFM) thickness and the interfacial coupling strength is tuned by inserting a ZnTe spacer layer with various thicknesses. Given the low Curie temperature ~100 K of the zinc-blende CrTe, a novel rock-salt structure of CrTe, which is predicted to be a half-metallic ferromagnet, is achieved by MBE growth. At last, intrinsic EB effects are observed in trigonal Cr2Te3 and monoclinic Cr3Te4 thin film, respectively. The antiferromagnetic component as well as the magnetic structure is explored via studying the EB effects.