The effect of chemical pressure upon the magnetism of (Ba 1− xSr x) 2PrNbCu 2O 8

Abstract

We present specific-heat and susceptibility measurements and a structural analysis of (Ba 1− x Sr x ) 2PrNbCu 2O 8 in order to explore the effect of the chemical pressure on the magnetic properties of the Pr sublattice. These systems are similar to PrBa 2Cu 3O 7−δ for which the Cu-O chain layers have been fully replaced by layers of Nb-O octahedra. The overall volume compression of - 5.5% across the series is found to be rather inhomogeneous yielding an anomalous expansion of the average Pr-O bond lenght of 3.8% which is accompanied by a reduction of T N from 11.6 K to 2.3 K. The variation of the magnetic properties across the solid solution is discussed in terms of hybridization of the Pr4f states with the Cu-O valence bands.