新型超导材料MgCNi_3的电子结构与超导电性研究

Study on the electronic structure and superconductivity of MgCNi_3

用MS Xα方法研究了非氧化物超导材料MgCNi3的电子结构 .研究结果显示 ,态密度分布曲线的主峰靠近Fermi面 ,主要来自于Ni的d电子的贡献 .用T(T =Co ,Mn ,Cu)替代MgCNi3中的部分Ni形成化合物MgCNi2 T ,替代使Ni的价电子数减小 ,价态发生变化 ,Fermi面处态密度N(EF)减小 .计算结果表明 :无论是电子掺杂 (Cu)还是空穴掺杂 (Co ,Mn) ,MgCNi3的超导电性都被抑制 ;Mn掺杂比Co掺杂更快地抑制超导电性 。

The electronic structures and superconductivity of a new superconducting perovskite material MgCNi 3 are studied using MS-Xα calculation. In MgCNi 3, the peak of density of states is located below the Fermi level, which is dominated by Ni d band. The electronic structures of MgCNi 2T(T=Co,Mn,Cu) have been also investigated. It is confirmed that Co dopants in MgCNi 3 behave as a source of d-band holes, and the suppression of superconductivity occurs faster for the Mn-doped case than for the Co-doped case. We study the effects of electron (Cu) doping on the superconductivity. It is found that both electron (Cu) doping and hole (Co, Mn) doping quench superconductivity. Comparing with the hole (Co) doping, we found that the suppression of superconductivity occurs faster for the Co-doped case than for the Cu-doped case.