Superconductivity in Doped sp3 Semiconductors: The Case of the Clathrates

D. Connétable (1) , V. Timoshevskii (1) , B. Masenelli (1) , J. Beille (2) , J. Marcus (3) , Bernard Barbara (2) , A. M. Saitta (4) , G.-M. Rignanese (5) , P. Mélinon (1) , S. Yamanaka (6) , X. Blase (1)

1 LPMCN - Laboratoire de Physique de la Matière Condensée et Nanostructures
2 LLN - Laboratoire Louis Néel
3 LEPES - Laboratoire d'Etudes des Propriétés Electroniques des Solides
4 LPMC - Laboratoire de Physique de la Matière Condensée
5 UCL PCPM - Unité de Physico-Chimie et de Physique des Matériaux
6 Faculty of Engineering, Hiroshima University - Department of Applied Chemistry

We present a joint experimental and theoretical study of the superconductivity in doped silicon clathrates. The critical temperature in Ba8@Si–46 is shown to strongly decrease with applied pressure. These results are corroborated by ab initio calculations using MacMillan's formulation of the BCS theory with the electron-phonon coupling constant lambda calculated from perturbative density functional theory. Further, the study of I8@Si–46 and of gedanken pure silicon diamond and clathrate phases doped within a rigid-band approach show that the superconductivity is an intrinsic property of the sp3 silicon network. As a consequence, carbon clathrates are predicted to yield large critical temperatures with an effective electron-phonon interaction much larger than in C60.

Mots clés: clathrates; diamond; ab initio; superconductivity

Domaines: Supraconductivité [cond-mat.supr-con]

D. Connétable, V. Timoshevskii, B. Masenelli, J. Beille, J. Marcus, et al.. Superconductivity in Doped sp3 Semiconductors: The Case of the Clathrates. Physical Review Letters, 2003, 91, pp.247001. ⟨10.1103/PhysRevLett.91.247001⟩. ⟨hal-00097746⟩