Superconductivity in doped sp3 semiconductors: the case of the clathrates.
We present a joint experimental and theoretical study of the superconductivity in doped silicon clathrates. The critical temperature in Ba(8)@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 I(8)@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 sp(3) 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.
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LPMCN, Université Claude Bernard Lyon I and CNRS, UMR 5586, Bâtiment Brillouin, 43 Bd du 11 Novembre 1918, 69622 Villeurbanne Cedex, France.
Timoshevskii
V
V
Masenelli
B
B
Beille
J
J
Marcus
J
J
Barbara
B
B
Saitta
A M
AM
Rignanese
G-M
GM
Mélinon
P
P
Yamanaka
S
S
Blase
X
X