Abstract
We substantiate by numerical and analytical calculations that the recently discovered superconductivity below 4 K in 3% boron-doped diamond is caused by electron-phonon coupling of the same type as in , albeit in three dimensions. Holes at the top of the zone-centered, degenerate -bonding valence-band couple strongly to the optical bond-stretching modes. The increase from two to three dimensions reduces the mode softening crucial for reaching 40 K in . Even if diamond had the same bare coupling constant as , which could be achieved with 10% doping, would be only 25 K. Superconductivity above 1 K in Si (Ge) requires hole doping beyond 5% (10%).
- Received 19 April 2004
DOI:https://doi.org/10.1103/PhysRevLett.93.237002
©2004 American Physical Society