Development of spintronic materials with multi-functionality

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(1) Reduced spin magnetic moment in half-metallic compounds : The magnetic and transport properties of bulk polycrystalline samples of Fe_2(Cr_<1-x>M_x)Si (M=Ti, V) Heusler conpounds have been investigated. These Fe-containing Heusler conpounds were found to be half-metals with low magnetic moment and large densities of states at the Fermi energy.(2) Strain effect in an antiferromagnetic Heusler compound : Strain effect on the properties of an antiferromagnetic Heusler compound Fe_2VSi was investigated. The strong enhancement in antiferromagnetic Neel temperatures T_N up to 193K was observed in coherently strained Fe_2VSi films.(3) Half-metallicity in an antiferromagnetic material : Coexistence of antiferromagnetism and high spin polarization has been found in bulk samples of double perovskite SrLaVMoO_6. The large enhancement in Neel temperatures T_N was observed in epitaxial SrLaVMoO_6 thin films. Experimental evidence of a half-metallic electronic structure was obtained from XPS study.(4) Experiments on half-metallic nano-hetero structures : We have developed the junction method using NbN as a superconducting electrode for measuring spin polarization of various ferromagnetic materials including half-metals. Application of this NbN junction method to Fe_4N, which was predicted to have current spin polarization P_σ of 1, resulted in DOS spin polarization P_<DOS> of -0.68. The NbN junction method was found to be a versatile technique which can simultaneously measure two types of spin polarization of P_<DOS> and P_σ.