A phenomenological model for the pressure sensitivity of the Curie temperature in hole-doped manganites

TL;DR

This paper develops a phenomenological model linking pressure, ionic radius, and electronic effects to the Curie temperature in hole-doped manganites, validated through experiments and literature data.

Contribution

It introduces a new phenomenological law that predicts the pressure sensitivity and structural dependence of the Curie temperature in manganites.

Findings

The model accurately predicts the pressure dependence of Tc.

It explains the influence of A-cation radius disorder on Tc.

The law aligns with a modified Double Exchange model considering polaronic effects.

Abstract

We performed high pressure experiments on La(0.8)Ca(0.2-x)Sr(x)MnO(3) (LCSMO) (0<x< 0.2) ceramic samples in order to analyze the validity of the well known relation between the A mean ionic radius (<rA>) and the Curie temperature Tc of hole-doped manganites at a fixed doping level and for doping values below the 0.3 (Mn+4/Mn+3) ratio. By considering our results and collecting others from the literature, we were able to propose a phenomenological law that considers the systematic dependence of Tc with structural and electronic parameters. This law predicts fairly well the pressure sensitivity of Tc, its dependence with the A-cation radius disorder and its evolution in the high pressure range. Considering a Double Exchange model, modified by polaronic effects, the phenomenological law obtained for Tc can be associated with the product of two terms: the polaronic modified bandwidth and an effective hole doping.