Electronic Structure of New Superconducting Perovskite MgCNi3

材料科学技术（英）, 2004, 20(2): 203-205.

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1.Physics and Microelectronic School, Shandong University, Jinan 250100, China；Department of Physics, Linyi Teachers University, Shandong 276005, China

2.Physics and Microelectronic School, Shandong University, Jinan 250100, China

3.Physics and Microelectronic School, Shandong University, Jinan 250100, China

基金项目: 国家高技术研究发展计划(863计划)(2002AA324050) 国家自然科学基金(90203013)

Electronic Structure of New Superconducting Perovskite MgCNi3

Keywords： Electronic structure

The electronic structures of new superconducting perovskite MgCNis and related compounds MgCNi2T (T=Co, Fe,and Cu) have been studied using MS-Xα method. In MgCNi3, the main peak of density of states is located below the Fermi level and dominated by Ni d. From the results of total energy calculations, it was found that the number of Ni valence electron decreases faster for the Fe-doped case than that for the Co-doped case. The valence state of Ni changes from +1.43 in MgCNi2Co to +3.02 in MgCNi2Fe. It was confirmed that Co and Fe dopants in MgCNi3 behave as a source of d-band holes and the suppression of superconductivity occurs faster for the Fe-doped case than that for the Co-doped case. In order to explain the fact that Co and Fe dopants in MgCNi3 behave as a source of d-band holes rather than magnetic scattering centers that quench superconductivity, we have also investigated the effects of electron (Cu) doping on the superconductivity and found that both electron (Cu) doping and hole (Co, Fe)doping quench superconductivity exist. Comparing with the hole (Co) doping, there was no much difference between Cu and Co doping. This suggests that Co and Fe doping do not actas magnetic impurity.

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Electronic Structure of New Superconducting Perovskite MgCNi3

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