Theoretical study of doped-Tl$_{2}$Mn$_{2}$O$_{7}$ and Tl$_{2}$Mn$_{2}$O$_{7}$ under pressure

TL;DR

This paper uses first-principles calculations to investigate how doping and pressure affect the magnetic and structural properties of Tl2Mn2O7, a pyrochlore compound with colossal magnetoresistance, explaining experimental observations.

Contribution

It provides a theoretical analysis of doping and pressure effects on Tl2Mn2O7, addressing experimental phenomena and structural changes.

Findings

Pressure suppresses ferromagnetic transition temperature.

Sb doping enhances ferromagnetism.

Structural changes under pressure are characterized.

Abstract

Using first-principles density functional based calculations, we study the effect of doping and pressure in manganese based pyrochlore compound,Tl$_{2}$Mn$_{2}$O$_{7}$ that exhibits colossal magneto-resistive behavior. The theoretical study is motivated by the counter-intuitive experimental observation of suppression of ferromagnetic transition temperature upon application of pressure and its enhancement upon substitution of Mn by moderate amount of nonmagnetic Sb ion. We also attempt to resolve the issue related to crystal structure changes that may occur upon application of pressure.