Magneto-optical reflectivity of superconducting MgB2 single crystals

A. Perucchi; L. Degiorgi; J. Jun; M. Angst; J. Karpinski

doi:10.1103/PhysRevLett.89.097001

paper

Magneto-optical reflectivity of superconducting MgB2 single crystals

arXiv:cond-mat/0205596 · doi:10.1103/PhysRevLett.89.097001

Abstract

We present magneto-optical reflectivity results in the basal-plane of the hexagonal $M g B_{2}$ . The data were collected on a mosaic of $M g B_{2}$ single crystals with $T_{c} = 38 K$ from the ultraviolet down to the far infrared as a function of temperature and magnetic field oriented along the c-axis. In the far infrared there is a clear signature of the superconducting gap with a gap-ratio $2 I^/ k_{B} T_{c} \sim 1.2$ , well below the weak-coupling value. The gap is suppressed in an external magnetic field, which is a function of temperature. We extract the upper critical field $H_{c 2}$ along the c-axis. The temperature dependence of $H_{c 2}$ is compatible with the Helfand-Werthamer behaviour.

6 pages (3 text-pages, 3 figures), submitted to PRL