Isomorphous PrT2B2C (T=Co,Ni,Pt) single crystals: Structural, transport, and magnetic properties

Abstract

The full substitution of Ni by Co and Pt enclosed in the same crystalline structure (I4/mmm) of Pr-based compounds have been investigated. The structural characteristics, magnetic properties, and magnetoresistance of PrCo2B2C, PrNi2B2C, and PrPt2B2C single crystals were studied to determine the reason for the absence or presence of superconductivity in those compounds. An antiferromagnetic transition was found for PrCo2B2C at about 8.5 K, where the easy magnetization axis is along the c-crystallographic direction whereas in PrNi2B2C the easy magnetization was at the ab plane. In PrNi2B2C a small magnetization without traces of saturation is found when it is measured up to 18 Tesla of applied magnetic field. This behavior suggests a screening effect as a result of a moderate hybridization between the conduction band and Pr ions. Superconductivity occurs in PrPt2B2C at about 6 K. The Pt-Pt distance and internal bonding angles are similar to those observed in the superconducting Ni-based compounds. Magnetoresistance measurements show positive and quadratic behavior (Delta rho/rho(0)similar to aH(2)) suggesting a spin fluctuation system. In the PrPt2B2C compound the electronic mean free path is smaller than the BCS coherence length (iota <epsilon) suggesting a dirty type II superconductor.