Magnetotransport and the upper critical magnetic field in MgB2

Abstract

Magnetotransport measurements are presented on polycrystalline MgB2 samples. The resistive upper critical magnetic field reveals a temperature dependence with a positive curvature from Tc = 39.3 K down to about 20 K, then changes to a slightly negative curvature reaching 25 T at 1.5 K. The 25- Tesla upper critical field is much higher than what is known so far on polycrystals of MgB2 but it is in agreement with recent data obtained on epitaxial MgB2 films. The deviation of Bc2(T) from standard BCS might be due to the proposed two-gap superconductivity in this compound. The observed quadratic normal-state magnetoresistance with validity of Kohler's rule can be ascribed to classical trajectory effects in the low-field limit.

6 pages, incl. 3 figures

References in corpus (6)

• Beyond Eliashberg superconductivity in MgB2: anharmonicity, two-phonon scattering, and multiple gaps
• Superconductivity in Dense $Mg{B}_2$ Wires
• Evidence for two superconducting energy gaps in MgB2 by point-contact spectroscopy
• Thin Film Magnesium Boride Superconductor with Very High Critical Current Density and Enhanced Irreversibility Field
• Superconducting Properties of MgB2 Bulk Materials Prepared by High Pressure Sintering
• Temperature- and magnetic-field-dependent resistivity of MgB2 sintered at high temperature and high pressure condition

Cited by in corpus (4)

• Point-contact spectroscopy of MgB2
• Anomalous metallic state above the upper critical field of the conventional three-dimensional superconductor AgSnSe2 with strong intrinsic disorder
• Superconducting ground state study of valence skip compound AgSnSe${}_2$
• Microwave Surface Resistance and Upper-Critical-Field Anisotropy of MgB2 Superconductor