Pressure dependence of the superconducting transition temperature of the filled skutterudite YFe4P12

Abstract

We have studied the pressure dependence of the superconducting transition temperature Tc of the filled skutterudite YFe4P 12 under various quasihydrostatic pressures up to 8 GPa. DC magnetization measurements up to 1.2 GPa in a piston-cylinder cell yields a linear increase of Tc with a positive coefficient dTc/dP = 1 K/GPa. Resistivity measurements up to 8 GPa in a cubic anvil apparatus show that Tc increases to 9.3 K at 8 GPa, but the slope decreases gradually with increasing pressure. Besides the previously reported LaFe 4P12, YFe4P12 becomes the second filled skutterudite superconductor that exhibits a positive pressure coefficient dTc/dP in a broad pressure range. The observed large dT c/dP > 0 of YFe4P12 can be rationalized by our band-structure calculations that show an enhancement of density of states at Fermi energy and the Hopfield parameter under pressure at least up to 8 GPa. On the other hand, similar calculations predict a dTc/dP < 0 for YRu4P12. © 2013 American Physical Society.