Electronic anisotropy, magnetic field-temperature phase diagram and their dependence on resistivity in c-axis oriented MgB2 thin films
/ Authors
S. Patnaik, L. Cooley, A. Gurevich, A. Polyanskii, J. Jiang, X. Cai, A. Squitieri, M. Naus, M. Lee, J. Choi
and 9 more authors
L. Belenky, S. D. Bu, J. Letteri, X. Song, D. Schlom, S. Babcock, C. Eom, E. Hellstrom, D. Larbalestier
/ Abstract
An important predicted, but so far uncharacterized, property of the new superconductor MgB2 is electronic anisotropy arising from its layered crystal structure. Here we report on three c-axis oriented thin films, showing that the upper critical field anisotropy ratio Hc2?/Hc2? is 1.8 to 2.0, the ratio increasing with higher resistivity. Measurements of the magnetic field-temperature phase diagram show that flux pinning disappears at H*?0.8Hc2?(T) in untextured samples. Hc2?(0) is strongly enhanced by alloying to 39 T for the highest resistivity film, more than twice that seen in bulk samples.
Journal: Superconductor Science and Technology