Superconductivity in diamond induced by boron doping at high pressure

Abstract

The application of hydrostatic pressure to boron‐doped diamond samples produces a linear decrease in the superconducting transition temperature Tc. The values d ln Tc/dP obtained for samples with different Tc's collapse near an average value –2 × 10–2 GPa–1, which is in reasonable agreement with theoretical predictions based on an electron–phonon mechanism of superconductivity in diamond within the virtual crystal approximation [Y. Ma et al., Phys. Rev. B 72, 014306 (2005)]. For the first time, superconducting boron‐doped diamond samples were synthesized with 10B and 13C isotopes. Isotopic substitution permits us to relate almost all bands in the Raman spectra of heavily boron‐doped diamond with the vibrations of carbon atoms. The “500 cm–1” Raman band shifts with both carbon and boron isotope substitutions and is associated with vibrations of clustered boron. We claim the presence of a carbon isotope effect in superconducting diamond. This fact supports the importance of the electron–phonon interaction as the mechanism of superconductivity in diamond. The value of the isotope effect coefficient is β0 = –d ln Tc/d ln M = 0.5 ± 0.3. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Superconductivity of boron-doped graphane under high pressure

“…Since boron (B) has one electron less than carbon, B dopant is an effective way to realize the metallization of carbon networks with hole-doping. [12][13][14][15][16] Boron dopant is also widely used to extend the applications of carbon materials, for example, B doped graphene has important applications in the elds of lithium storage 17,18 and catalysts 19 Furthermore, since the electronic states of the B-C sigma bonds will cross the Fermi level. For example, B dopant can turn diamond into superconductor with the T c of $4 K, 12 where sigma bond plays an important role.…”