NOVEL SPINTRONIC MATERIALS BASED ON FERROMAGNETIC SEMICONDUCTOR CHALCOPYRITES

Abstract

Ternary diamond-like compounds in II–IV–V2 semiconductor system heavily-doped with transition d-element Mn have been recently prepared. The materials grown in both forms — single crystal layers and polycrystalline bulks — exhibit well defined ferromagnetic hysteresis with a saturation behavior in the magnetization curve up to above room temperature. Curie temperatures are of TC=310 K to 320 K for ( Cd 1-x Mn x) GeP 2 and ( Zn 1-x Mn x) GeP 2 compounds. The chemical states in the bulk of ZnGeP 2: Mn and interface of Mn -doped ferromagnetic layer on ZnGeP 2 (001) crystal, have been clarified by electron paramagnetic resonance and in situ photoemission spectroscopy. The as-prepared surface consists of Ge -rich, metallic Mn -compound. In and below the sub-surface region, dilute Mn 2+ species as precursors of the DMS phase exist. Mn 2+ ions are paramagnetic active on Zn 2+ sites in the bulk and show five EPR sets of equidistant peaks. Theoretical band-gap calculation suggests a predominant antiferromagnetic order in stoichiometric ( Cd , Mn ) GeP 2 but the systems with vacancies as ( Cd , V C , Mn ) GeP 2 or ( Cd , Ge , Mn ) GeP 2 are ferromagnetic and energetically stable. These materials are of great promise for room-temperature spintronics applications.