Magnetoresistance of a layered high- Tc superconductor below the Berezinskii-Kosterlitz-Thouless transition

• Published in: Physica. C, Superconductivity Superconductivity, 1992-04, Vol.193 (1), p.47-54
• Main Authors: Artemenko, S.N., Gorlova, I.G., Latyshev, Yu.I.
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Physics; Properties of type I and type II superconductors; Superconductivity
• ISSN: 0921-4534; 1873-2143
• DOI: 10.1016/0921-4534(92)90867-C

The mechanism of the resistivity of a weakly coupled layered supecocoductor below the Berezinskii-Kosterlitz-Thouless (BKT)_ transition temperature T BKT in a magnetic field perpendicular to the layers is studied experimentally and theoretically. The resistance of Bi 2Sr 2CaCu 2 O x single crystals at temperatures 70–90 K in a magnetic field H< kOe was measured. At T < T BKT in a field H larger than 10–30 Oe the resistance is characterized by the thermoactivated behaviour down to some characteristic temperature T ∗(H) , below which power-law I− V curves V∝ I aH( T)+1 were observed. We account for these results by the creation of 2D-vortices due to the breaking of Abrikosov vortex lines by thermal fluctuations and transport current. Calculated dependences of the power index a H on the temperature and magnetic field agree with the experimental ones. The observed T ∗(H) dependence is described by the condition that the mean thermal fluctuations of the positions of the 2D-vortices forming flux lines are of the order of a mean distance between flux lines.