Structural, transport, magnetic properties and Raman spectroscopy of orthorhombic Y$1-x$CaxMnO3(0 <= x <= 0.5)

TL;DR

This study investigates how calcium doping affects the structural, magnetic, electrical, and vibrational properties of orthorhombic Y$_{1-x}$Ca$_x$MnO$_3$ across a range of compositions, revealing systematic changes and disorder effects.

Contribution

It provides a comprehensive analysis of the effects of Ca doping on YMnO$_3$, including structural, magnetic, electrical, and Raman spectral properties, highlighting disorder and magnetic transition phenomena.

Findings

Lattice parameters vary systematically with Ca content.

Electrical conductivity increases with doping but remains semiconducting.

Magnetic interactions shift from antiferromagnetic to ferromagnetic around x=0.08.

Abstract

Orthorhombic Y$_{1-x}$Ca$_x$MnO$_3$ ($0 \leq x \leq 0.5$) was prepared under high pressure and the variations with $x$ of its structural, magnetic, electrical properties and the polarized Raman spectra were investigated. The lattice parameters change systematically with $x$. Although there are strong indications for increasing disorder above $x = 0.20$, the average structure remains orthorhombic in the whole substitutional range. Ca doping increases conductivity, but temperature dependence of resistivity $\rho$(T) remains semiconducting for all $x$. The average magnetic exchange interaction changes from antiferromagnetic for $x < 0.08$ to ferromagnetic for $x > 0.08$. The evolution with $x$ of the Raman spectra provides evidence for increasingly disordered oxygen sublattice at $x \geq 0.10$, presumably due to quasistatic and/or dynamical Jahn-Teller distortions.