Critical current behavior of superconducting MoN and Mo3 Sb7 microfibers
Abstract
We present the transport and critical current measurements on carbon microfibers coated with 40-nm of polycrystalline δ-MoN and on carbon microfibers coated with 160 nm of Mo3 Sb7. In each case the coatings where synthesized directly onto the 6-μm diameter carbon fibers. The superconducting transition temperature of the MoN microfibers was Tc ∼13.1K, which is the highest temperature reported in any thin film form and is higher than what was reported for stoichiometric δ-MoN, produced by high pressure synthesis. The transition temperature of the Mo3 Sb7 -coated microfibers Tc =7.5K was significantly higher than that observed in powder samples. Near the transition temperature Tc, the critical current density Jc for both systems was well described by the power-law form [1- (T/ Tc) 2] α, where α=1.5 is the Ginzburg-Landau exponent. We extrapolated Jc (0) ≈5× 107 A/ cm2 for the MoN microfibers and Jc (0) ≈2.5× 105 A/ cm2 for the Mo3 Sb7 fibers. © 2008 The American Physical Society.