The effect of Cu-doping on the magnetic and transport properties of La0.7Sr0.3MnO3

TL;DR

This study investigates how Cu-doping influences the structural, magnetic, and transport properties of La0.7Sr0.3MnO3, revealing changes in structure, magnetic interactions, and a metal-insulator transition at higher doping levels.

Contribution

It provides new insights into the effects of Cu substitution on the structural and magnetic properties of La0.7Sr0.3MnO3, including the identification of Cu3+ ions and the impact on magnetoresistance.

Findings

All samples maintain rhombohedral structure from 10K to RT.

Cu doping induces a metal-insulator transition at x > 0.15.

Maximum magnetoresistance of 80% observed at x = 0.15.

Abstract

The effects of Cu-doping on the structural, magnetic, and transport properties of La0.7Sr0.3Mn1-xCuxO3 (0 < x < 0.20) have been studied using neutron diffraction, magnetization and magnetoresistance (MR) measurements. All samples show the rhombohedral structure with the R3c space-group from 10K to room temperature (RT). Neutron diffraction data suggest that some of the Cu ions have a Cu3+ state in these compounds. The substitution of Mn by Cu affects the Mn-O bond length and Mn-O-Mn bond angle resulting from the minimization of the distortion of the MnO6 octahedron. Resistivity measurements show that a metal to insulator transition occurs for the x more than 0.15 samples. The x = 0.15 sample shows the highest MR(_80%), which might result from the co-existence of Cu3+/Cu2+ and the dilution effect of Cu-doping on the double exchange interaction.