Transition Temperature and Magnetoresistance in Double-Exchange Compounds with Moderate Disorder

Abstract

We develop a variational mean-field theory of the ferromagnetic transition in compounds like Lanthanum-Manganite within the framework of the Double-Exchange Model supplemented by modest disorder. We obtain analytical expressions for the transition temperature, its variation with the valence electron-density and its decrease with disorder. We derive an expression for the conductivity for both the paramagnetic and the ferromangetic metallic phases, and study its dependence on the temperature and magnetic field. A simple relation between the resistivity in the ferromagnetic phase and the spontaneous magnetization is found. Our results are in a good agreement with the experimental data on transition temperatures and resistivity in the manganite compounds with relatively small disorder. We comment on the effects of increased disorder.

References in corpus (4)

• Carrier Density Collapse and Colossal Magnetoresistance in Doped Manganites
• Charge melting and polaron collapse in $L{a}_{1.2}S{r}_{1.8}M{n}_2{O}_7$
• Optical spectral weights and the ferromagnetic transition temperature of CMR manganites: relevance of double-exchange to real materials
• Colossal Magnetoresistance using the Small Polaron Picture with Finite Bandwidth Effects

Cited by in corpus (7)

• Monte Carlo Study of Doping Change and Disorder Effect on Double Exchange Ferromagnetism
• Transport and Localisation in the Presence of Strong Structural and Spin Disorder
• Inhomogeneous Ferromagnetism and Unconventional Charge Dynamics in Disordered Double Exchange Magnets
• Double Exchange Models: Self Consistent Renormalisation
• Colossal magnetoresistance and quenched disorder in manganese oxides
• An Origin of CMR: Competing Phases and Disorder-Induced Insulator-to-Metal Transition in Manganites
• Substitutional disorder and charge localization in manganites