Lee K-W, Pickett W E
Department of Physics, University of California, Davis, CA 95616, USA.
Phys Rev Lett. 2004 Dec 3;93(23):237003. doi: 10.1103/PhysRevLett.93.237003. Epub 2004 Nov 30.
Superconductivity of boron-doped diamond, reported recently at T(c)=4 K, is investigated exploiting its electronic and vibrational analogies to MgB2. The deformation potential of the hole states arising from the C-C bond-stretch mode is 60% larger than the corresponding quantity in MgB2 that drives its high T(c), leading to very large electron-phonon matrix elements. The calculated coupling strength lambda approximately 0.5 leads to T(c) in the 5-10 K range and makes phonon coupling the likely mechanism. Higher doping should increase T(c) somewhat, but the effects of three dimensionality primarily on the density of states keep doped diamond from having a T(c) closer to that of MgB2.
最近报道的硼掺杂金刚石在T(c)=4 K时的超导性，利用其与MgB2的电子和振动相似性进行了研究。由C-C键拉伸模式产生的空穴态的形变势比驱动其高T(c)的MgB2中的相应量大约60%，导致非常大的电子-声子矩阵元。计算出的耦合强度λ约为0.5，导致T(c)在5-10 K范围内，并使声子耦合成为可能的机制。更高的掺杂应该会使T(c)有所增加，但三维性主要对态密度的影响使掺杂金刚石的T(c)无法更接近MgB2的T(c)。
