Superconducting Properties of MgB2 Thin Films Prepared on Flexible Plastic Substrates

130 LLE Review, Volume 91 The recent discovery of superconductivity at 39 K in hexagonal magnesium diborides1 has stimulated very intensive investigations of the fundamental mechanism of superconductivity in MgB2 as well as the possible practical applications of this new superconductor. In comparison with high-temperature cuprates, MgB2 superconductors have more than two-timeslower anisotropy, significantly larger coherence length, and higher transparency of grain boundaries to the current flow. At the same time, when compared to conventional metallic superconductors (including Nb3Sn or NbN), they have at least twotimes-higher critical temperature Tc and energy gap, as well as higher critical current density Jc. As a result, MgB2 superconductors are expected to play an important role for high-current, high-field applications, as well as in cryoelectronics, where they might be the material-of-choice for above-300-GHz clockrate digital electronics. In addition, MgB2 devices could operate in simple cryocoolers.