Critical current behavior of superconducting MoN and Mo3 Sb7 microfibers

A. B. Karki, Louisiana State University
D. P. Young, Louisiana State University
P. W. Adams, Louisiana State University
E. K. Okudzeto, Louisiana State University
Julia Y. Chan, Louisiana State University


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.