2006/04/13 by F. Giubileo, Filippo Giubileo, F. Bobba +9
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:10.1103/physrevb.76.024507
published as Physical Review B 76, 024507 (2007) · 4 pages, 3 figures
arxiv created 2006/04/13 · openalex publication_date 2007/07/13 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
We have performed an extensive study of the temperature and magnetic field dependencies of local tunneling spectra measured by means of variable temperature scanning tunneling spectroscopy on high quality Mg_1\ensuremath-xAlxB2 single crystals. Single gap conductance spectra due to c-axis tunneling were measured, probing different amplitudes of the three-dimensional \ensuremathΔ_\ensuremathπ as a function of Al content (i.e., as a function of the critical temperature TC). We give clear evidence that the locally measured energy gap, as well as the upper critical field, reach maximum values \ensuremathΔ_\ensuremathπ=2.4\phantom\rule0.3em0exmeV and Hc2\ensuremath\geqslant3\phantom\rule0.3em0exT around x\ensuremath≃0.1 (TC=33\phantom\rule0.3em0exK) regardless of the monotonous fall of TC as a function of doping. Our results strongly suggest that different interband scattering occurs for different gap amplitudes.