Coexistence of high electrical conductivity and weak ferromagnetism in Cr doped y 2 Ir 2 O 7 pyrochlore iridates

Abstract

We report the structural, magnetic, and electrical transport properties of Y 2 Ir 2 - x Cr x O 7 pyrochlore iridates. Chemical doping leads to the order of magnitude enhancement of electrical conductivity. The introduction of Cr 3 + at the Ir 4 + site tends to distort the Ir - O 6 octahedra and weakens antiferromagnetic correlation. The x-ray photoemission spectroscopy measurements suggest the coexistence of Ir 4 + and Ir 5 + valence states in the Y 2 Ir 2 - x Cr x O 7 compounds. The concentration of Ir 5 + is enhanced with Cr doping, leading to weak ferromagnetism and enhanced electrical conductivity. A cluster-glass-like transition is also observed at low temperatures with Cr doping, possibly due to competing ferromagnetic and antiferromagnetic interaction.