2001/04/12 by D. G. Hinks, H. Claus, J. D. Jorgensen · 7 citations
Materials Science · Physics and Astronomy · #Iron-based superconductors research #Physics of Superconductivity and Magnetism #Superconductivity in MgB2 and Alloys #cond-mat.supr-con
paper · pdf · doi:10.1038/35078037
published as Nature,411,457-460 (2001) · 8 pages, 3 figures
arxiv created 2001/04/12 · openalex publication_date 2001/05/01 · arxiv updated 2009/11/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The recent discovery of superconductivity at ~39 K in MgB2, by Nagamatsu et al. establishes this simple binary compound as having the highest bulk superconducting transition temperature, Tc, of any non-copper-oxide material. Much of the initial research has focused on whether MgB2 is a conventional BCS, electron-phonon mediated superconductor, and, if it is, why Tc is so high. Isotope effect measurements, in which the atom masses are manipulated to systematically change the phonon frequencies, are one of the fundamental experimental tests of electron-phonon mediated superconductivity. One would expect the total isotope effect coefficient, i.e. the sum of both the Mg and B coefficients, to be 1/2 for a high- Tc, phonon mediated, simple sp orbital superconductor like MgB2. We find a value of 0.32(1), much reduced from the canonical BCS value of 0.5. This requires large values of l (electron-phonon coupling constant) and m* (repulsive electron-electron pseudopotential) to account for the high Tc and, thus, constrains any theoretical model for superconductivity in MgB2.