Carbon doping in MgB2: role of boron and carbon px(y) bands |
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Authors: | Prabhakar P. Singh |
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Affiliation: | Department of Physics, Indian Institute of Technology, Powai, Mumbai 400076, India |
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Abstract: | We have studied the changes in the electronic structure and the superconducting transition temperature Tc of Mg(B1−xCx)2 alloys as a function of x with 0≤x≤0.3. Our density-functional-based approach uses the coherent-potential approximation to describe the effects of disorder, the Gaspari-Gyorffy formalism to estimate the electron-phonon matrix elements and the Allen-Dynes equation to calculate Tc in these alloys. We find that the changes in the electronic structure of Mg(B1−xCx)2 alloys, especially near the Fermi energy EF, come mainly from the outward movement of EF with increasing x, and the effects of disorder in the B plane are small. In particular, our results show a sharp decline in both B and C px(y) states for 0.2≤x≤0.3. Our calculated variation in Tc of Mg(B1−xCx)2 alloys is in qualitative agreement with the experiments. |
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Keywords: | 74.25.Kc 63.20.Kr |
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