Magnetic and high-pressure studies in the YPd2B2C system

The macroscopic properties of the superconducting phase YPd2B2C in the mult iphase compound YPd5B3C0.3 have been investigated. The onset of superconduc tivity was observed at 22.6 K, zero resistance at 21.2 K, the lower critica l field H-cl at 0 K was estimated to be H-cl(0) similar to 310 G and the co mpound was found to be an extreme type-II superconductor with the upper cri tical field in excess of 50 000 G below 15 K. At T = 15 K, the Ginzburg-Lan dau parameter was determined to be kappa > 9 corresponding to a coherence l ength xi similar to 80 Angstrom and magnetic penetration depth of 800 Angst rom. The superconducting transition temperature T-c(P) was also measured un der hydrostatically applied pressure. T-c(P) of YPd2B2C decreases linearly with dT(c)/dP similar to -9 x 10(-2) K/kbar. The discussion of T-c(P) will focus on the influence pressure has on the phonon spectrum and the density of states near the Fermi level. (C) 1999 Published by Elsevier Science B.V. All rights reserved.