2000/02/14 by Evgenii E. Narimanov, E. E. Narimanov, C. M. Varma
Chemistry · Materials Science · Physics and Astronomy · #Advanced Condensed Matter Physics #Chemistry #Condensed matter physics #Electrical resistivity and conductivity #Electrode #Ferromagnetism #Lanthanum manganite #Magnetic and transport properties of perovskites and related materials #Magnetic field #Magnetization #Magnetoresistance #Manganite #Materials science #Paramagnetism #Phase transition #Physics #Quantum mechanics #Rare-earth and actinide compounds #Superconductivity #Transition temperature #Valence (chemistry) #cond-mat.mtrl-sci #cond-mat.str-el
paper · pdf · doi:10.1103/physrevb.65.024429
arxiv created 2000/02/14 · openalex publication_date 2001/12/19 · arxiv updated 2021/05/26 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
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 ferromagnetic 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.