Carbon doping in MgB2: role of boron and carbon px(y) bands

✍ Scribed by Prabhakar P. Singh

• Publisher: Elsevier Science
• Year: 2003
• Tongue: English
• Weight: 142 KB
• Volume: 127
• Category: Article
• ISSN: 0038-1098
• DOI: 10.1016/s0038-1098(03)00426-5

✦ Synopsis

We have studied the changes in the electronic structure and the superconducting transition temperature T c of MgðB 12x C x Þ 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 T c in these alloys. We find that the changes in the electronic structure of MgðB 12x C x Þ 2 alloys, especially near the Fermi energy E F ; come mainly from the outward movement of E F 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 p xðyÞ states for 0:2 # x # 0:3: Our calculated variation in T c of MgðB 12x C x Þ 2 alloys is in qualitative agreement with the experiments.