摘要:
利用第一性原理计算方法,研究了CuHg2 Ti结构下Ti2 CrK (K =Sb, Ge, Sn, Sb, Bi)系列合金的电子结构、能隙起源和磁性。研究发现: Ti2 CrK (K =Si, Ge)合金是普通半导体材料; Ti2 CrK (K =Si, Bi)合金是亚铁磁性半金属材料,其半金属性能隙受到Sb 和Bi 原子s 态的直接影响; Ti2CrSn合金是完全补偿的亚铁磁性半导体。基于Ti2 CrSn合金两个自旋方向上的能隙起源不同,通过Si和Ge替换掺杂同族Sn元素调制能隙的宽度,获得了完全补偿亚铁磁性自旋无能隙材料;通过Fe和Mn替换掺杂过渡族Cr元素获得了一系列半金属材料。 Ti2Cr1?xFexSn 和Ti2Cr1?xMnxSn合金都具有亚铁磁性。所研究的这些半金属性合金的分子磁矩Mtotal 与总的价电子数Zt服从Mtotal=Zt?18规则。
Abstract:
The electronic structures, band-gap origins and magnetisms of Ti2Cr-based alloys with CuHg2Ti-type structure are studied using the first principles calculations. It is found that Ti2CrK (K =Si, Ge) alloys are semiconductors Ti2CrK (K =Sb, Bi) alloys are predicted to be half-metallic ferrimagnets and their half-metallic band gaps are affected directly by the S states of Sb and Bi atoms. Ti2CrSn alloy is a completely-compensated ferrimagnetic semiconductor. Due to the different band-gap origins of Ti2CrSn alloy in two spin directions, we can adjust the width of band gap by doping engineering. The ferrimagnetic spin-gapless materials are achieved by substituting Si or Ge for Sn. Substituting Fe or Mn for Cr, we gain a series of half-metallic materials. Ti2Cr1?xFexSn and Ti2Cr1?xMnxSn alloys are in ferrimagnetic states. All the half-metallic Ti2Cr-based alloys follow Mtotal =Zt?18 rule (Mtotal is the total magnetic moment and Zt is the valence concentration).