Resonant Soft X-Ray Emission Spectroscopy of Vanadium Oxides and Related Compounds

摘要: In today's information world, bits of data are processed by semiconductor chips, and stored in the magnetic disk drives. But tomorrow's technology may see magnetism (spin) semiconductivity (charge) combined one ''spintronic'' device that exploits both charge ''spin'' to carry (the best two worlds). Spintronic devices such as spin valve transistors, light emitting diodes, non-volatile memory, logic devices, optical isolators ultra-fast switches some areas interest for introducing ferromagnetic properties at room temperature a make it multifunctional. The potential advantages spintronic will be higher speed, greater efficiency, better stability reduced power consumption. This Thesis contains main topics: In-depth understanding Mn doped ZnO, our search identification least six new above semiconductors. Both complex ZnO based materials, well number nonoxides like phosphides, sulfides suitably with or Cu shown give rise ferromagnetism temperature. Some highlights this work discovery in: (1) ZnO:Mn (paper Nature Materials, Oct issue, 2003); (2) (containing no elements it); (3) GaP (again containing (4) Enhancement Magnetization co-doping ZnO:Mn; (5) CdS Mn, few others not reported thesis. We discuss detail first observation form powder, bulk pellets, 2-3 {micro}m thick transparent pulsed laser deposited films (< 4 at.%) ZnO. High-resolution transmission electron microscopy (HRTEM) energy loss spectroscopy (EELS) spectra recorded from 2 200nm showed homogeneous distribution substituting Zn 2{sup +} state lattice. Ferromagnetic Resonance (FMR) technique is used confirm existence ordering temperatures high 425K. ab initio calculations were found consistent arising fully polarized state. key observed system low processing, which prevents formation clusters, secondary phases host becoming n-type. electronic structure same thin studied using XAS, XES RIXS. revealed strong hybridization between 3d O 2p states, an important characteristic Dilute Semiconductor (DMS). It various processing conditions sintering temperature, dopant concentration precursors making DMS have great influence on final properties. Use experimental techniques verify physical properties, understand mechanism involved presented. Methods improve moment also described. New promising materials (such explored). demonstrated capability fabricate semiconductors thus makes possible realization wide range variety multifunctional phenomena related magneto-optic components.