IrSr_2Sm_{1.15}Ce_{0.85}Cu_{2.175}O_{10}: A Novel Reentrant Spin-Glass Material

TL;DR

This study reports the synthesis and characterization of a new iridium-based layered cuprate exhibiting reentrant spin-glass behavior, complex magnetic transitions, and semiconducting properties with notable negative magnetoresistance.

Contribution

The paper introduces a novel iridium-containing layered cuprate with detailed structural and magnetic analysis, revealing reentrant spin-glass behavior and magnetoresistance properties.

Findings

Reentrant spin-glass ground state confirmed by susceptibility measurements.

Material exhibits semiconducting behavior with no superconductivity.

Negative magnetoresistance increases at low temperatures, reaching -9% at 8 K.

Abstract

A new iridium containing layered cuprate material, IrSr_2Sm_{1.15}Ce_{0.85}Cu_{2.175}O_{10, has been synthesized by conventional ambient-pressure solid-state techniques. The material's structure has been fully characterized by Rietveld refinement of high resolution synchrotron X-ray diffraction data; tilts and rotations of the IrO_6 octahedra are observed as a result of a bond mismatch between in-plane Ir-O and Cu-O bond lengths. DC-susceptibility measurements evidence a complex set of magnetic transitions upon cooling that are characteristic of a reentrant spin-glass ground-state. The glassy character of the lowest temperature, Tg=10 K, transition is further confirmed by AC-susceptibility measurements, showing a characteristic frequency dependence that can be well fitted by the Vogel-Fulcher law and yields a value of \Delta_(T_f)/[T_f \Delta log({\omega})] =0.015(1), typical of dilute magnetic systems. Electronic transport measurements show the material to be semiconducting at all temperatures with no transition to a superconducting state. Negative magnetoresistance is observed when the material is cooled below 25 K, and the magnitude of this magnetoresistance is seen to increase upon cooling to a value of MR = -9 % at 8 K.