Scanning Tunneling Spectroscopy on Single Crystal MgB2

Abstract

We report on the results of scanning tunneling spectroscopy measurements on single crystals of Mg2. Tunneling was performed both parallel and perpendicular to the crystalline c-axis. In the first case, a single superconducting gap (Delta_pi = 2.2 meV) associated with the pi-band is observed. Tunneling parallel to the ab-plane reveals an additional, larger gap (Delta_sigma ~ 7 meV) originating in the highly two-dimensional sigma-band. Vortex imaging in the pi-band was performed with the field and tunnel current parallel to the c-axis. The vortices have a large core size compared to estimates based on Hc2, and show an absence of localized states in the core. Furthermore, superconductivity between the vortices is rapidly suppressed by an applied field. A comparison to specific heat measurements is performed.

12 pages, 7 figs. Submitted to Physica C

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• Systematic study of the two band/two gap superconductivity in carbon-substituted MgB2 by point-contact spectroscopy
• c-axis Raman Scattering in MgB2: Observation of a Dirty-Limit Gap in the pi-bands
• BCS-BEC crossover of collective excitations in two-band superfluids
• On the rate of Tc suppression by the interband impurity scattering in MgB2
• Reply to Comment by E. Babaev and M. Silaev, arXiv:1105.3756
• Layered superconductor in a magnetic field: breakdown of the effective masses model
• Wafer-Scale MgB2 Superconducting Devices
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