Influence of itinerancy on the magnetic properties of the single crystals of Sr2YRu1-xCuxO6 solid solutions

TL;DR

This study investigates how Cu substitution in Sr2YRu1-xCuxO6 affects its lattice structure, magnetic properties, and potential superconductivity, revealing complex magnetic transitions and signs of weak superconductivity linked to itinerant holes and lattice distortions.

Contribution

It provides new insights into the magnetic and superconducting behavior of Sr2YRu1-xCuxO6 solid solutions with detailed spectroscopic and magnetic analyses.

Findings

Cu replaces Ru, causing lattice distortion and itinerant holes.

Observation of antiferromagnetic and diamagnetic transitions at 32 K.

Evidence of weak superconductivity and spin-glass behavior.

Abstract

X-ray absorption spectroscopy(XAS) Ru L-edge and O K-edge measurements on single crystals of Sr2YRu1-xCuxO6 (x=0.01-0.05) solid solutions show that Cu replaces Ru in the lattice which results in a lattice distortion and itinerant holes that increase with increasing x. Powder X-ray diffraction (XRD) measurements confirm the lattice distortion through changes in the lattice parameters. Magnetic measurements reveal an antiferromagnetic transition at 32 K in the crystals with x=0 and a diamagnetic transition at 32 K for x \geq 0.01indicative of superconductivity in the zero field cooled (ZFC) curves. The field cooled (FC) curves show a weak ferromagnetic character with x=0 and a ferromagnetic transition at 30 K and an antiferromagnetic transition at 23 K in the presence of Cu. The peak at 30 K in the ac susceptibility measurements indicates a spin-glass behavior. The low field part of the M-H curve for x=0.05 crystal indicates weak superconductivity. The shifting of the M-H curve on FC indicates spin-glass state. In conjunction with the XAS results the magnetic behavior is explained in terms of a spontaneous vortex state as a result of the non-freezing Ru5+ spins.