Development of spintronic materials with multi-functionality

(1)半金属化合物中自旋磁矩的降低：研究了Fe_2(Cr_<1-x>M_x)Si (M=Ti， V) Heusler化合物的体多晶样品的磁性和输运性质。这些含铁的Heusler化合物被发现是半金属，具有低磁矩和在费米能量下的大密度态。(2)反铁磁Heusler化合物中的应变效应：研究了应变对反铁磁Heusler化合物Fe_2VSi性能的影响。在相干应变Fe_2VSi薄膜中观察到反铁磁Neel温度T_N提高到193K。(3)反铁磁性材料的半金属性：在双钙钛矿SrLaVMoO_6的大块样品中发现了反铁磁性和高自旋极化共存的现象。在SrLaVMoO_6外延薄膜中观察到Neel温度T_N的显著提高。从XPS研究中获得了半金属电子结构的实验证据。(4)半金属纳米异质结构实验：我们开发了以NbN作为超导电极的结法，用于测量包括半金属在内的各种铁磁性材料的自旋极化。将这种NbN结法应用于Fe_4N上，得到了DOS自旋极化P_<DOS>为-0.68。NbN结法是一种多功能的方法，可以同时测量P_<DOS>和P_σ两种自旋极化。

(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.