Structural, magnetic and electrical properties of single crystalline La_(1-x)Sr_xMnO_3 for 0.4 < x < 0.85

TL;DR

This study investigates the structural, magnetic, and electrical properties of Sr-doped LaMnO_3 single crystals across a range of doping levels, revealing complex phase behavior influenced by orbital degrees of freedom and identifying various magnetic and electronic phases.

Contribution

It provides new insights into the phase diagram of La_(1-x)Sr_xMnO_3, highlighting the role of orbital order and identifying the existence of a monoclinic antiferromagnetic metallic phase.

Findings

Discovery of a ferromagnetic metal near x=0.6

Identification of a monoclinic antiferromagnetic metallic phase

Observation of an antiferromagnetic insulator at higher doping levels

Abstract

We report on structural, magnetic and electrical properties of Sr-doped LaMnO_3 single crystals for doping levels 0.4 < x < 0.85. The complex structural and magnetic phase diagram can only be explained assuming significant contributions from the orbital degrees of freedom. Close to x = 0.6 a ferromagnetic metal is followed by an antiferromagnetic metallic phase below 200 K. This antiferromagnetic metallic phase exists in a monoclinic crystallographic structure. Following theoretical predictions this metallic antiferromagnet is expected to reveal an (x^2-y^2)-type orbital order. For higher Sr concentrations an antiferromagnetic insulator is established below room temperature.