Pressure effects on the transition temperature of superconducting MgCxNi3

Abstract

The effect of hydrostatic pressure (P) up to 17 kbar on the superconducting transition temperature (T-C) of the newly discovered intermetallic nonoxide perovskite superconductor MgCxNi3 has been reported. T-C is found to increase with increasing P at a rate of dT(C)/dPsimilar to0.0134 to 0.0155 K/kbar depending on the value of carbon content x. The absolute value of dT(C)/dP for MgCxNi3 is about the same as that of intermetallic RNi2B2C (R denotes rare earth) and metallic superconductors but about one order of magnitude smaller than that of the most recently and intensively studied superconductor MgB2. However, the d ln T-C/dPsimilar to0.001 81 to 0.002 24 kbar(-1) and the rate of change of T-C with unit cell volume (V), d ln T-C/d ln Vsimilar to-3.18 to -2.58 of MgCxNi3 are having the comparable magnitude to that of MgB2 with opposite sign. The increase of T-C with P in MgCxNi3 can be explained in the framework of density of states (DOS) effect.