title: Scanning tunneling spectroscopy in MgB2.
abstract: We present scanning tunneling microscopy measurements of the surface of superconducting MgB2 with a critical temperature of 39 K. In zero magnetic field the conductance spectra can be analyzed in terms of the standard BCS theory with a smearing parameter gamma. The value of the superconducting gap is 5 meV at 4.2 K, with no experimentally significant variation across the surface of the sample. The temperature dependence of the gap follows the BCS form, fully consistent with phonon-mediated superconductivity in this novel superconductor. The application of a magnetic field induces strong pair breaking as seen in the conductance spectra in fields up to 6 T.
authors.affiliation: Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA.
authors.forename: G
authors.initials: G
authors.lastname: Karapetrov
authors.forename: M
authors.initials: M
authors.lastname: Iavarone
authors.forename: W K
authors.initials: WK
authors.lastname: Kwok
authors.forename: G W
authors.initials: GW
authors.lastname: Crabtree
authors.forename: D G
authors.initials: DG
authors.lastname: Hinks