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Covalent superconductors are superconducting materials where the atoms are linked by covalent bonds. The first such material was synthetic diamond grown by the high-pressure high-temperature (HPHT) method.〔 L. Boeri, J. Kortus and O. K. Andersen ("Three-Dimensional MgB2-Type Superconductivity in Hole-Doped Diamond" ), K.-W. Lee and W. E. Pickett ("Superconductivity in Boron-Doped Diamond" ), X. Blase, Ch. Adessi and D. Connetable ("Role of the Dopant in the Superconductivity of Diamond" ), E. Bustarret et al. ("Dependence of the Superconducting Transition Temperature on the Doping Level in Single-Crystalline Diamond Films" ) - free download〕 The discovery had no practical importance, but surprised most scientists as superconductivity had not been observed in covalent semiconductors, including diamond and silicon. ==Diamond== Superconductivity in diamond was achieved through heavy p-type doping by boron such that the individual doping atoms started interacting and formed an "impurity band". The superconductivity was of type-II with the critical temperature Tc = 4 K and critical magnetic field Hc = 4 T. Later, Tc ~ 11K has been achieved in homoepitaxial CVD films. Regarding the origin of superconductivity in diamond, three alternative theories exist at the moment: conventional BCS theory based on phonon-mediated pairing, correlated impurity band theory and spin-flip-driven pairing of holes weakly localized in the vicinity of the Fermi level. Whereas there is no solid experimental support for either model, recent accurate measurements of isotopic shift of the transition temperature Tc upon boron and carbon isotopic substitutions favor the BCS theory. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Covalent superconductor」の詳細全文を読む スポンサード リンク
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