Dimensional crossover and the magnetic transition in electron doped manganites

Abstract

We introduce a microscopic model for electron doped manganites that explains the mechanism of the observed transition from $G$-type antiferromagnetic ($G$-AF) to $C$-type antiferromagnetic ($C$-AF) order under increasing doping by double exchange mechanism. The model unravels the crucial role played by $e_g$ orbital degrees of freedom and explains the observed metal-to-insulator transition by a dimensional crossover at the magnetic phase transition. The specific heat and the spin canting angle found for the $G$-AF phase agree with the experimental findings. As a surprising outcome of the theory we find that spin canting is suppressed in the $C$-AF phase, in agreement with the experiment, due to the Fermi surface topology.

5 pages, 4 figures

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• Fingerprints of spin-orbital polarons and of their disorder in the photoemission spectra of doped Mott insulators with orbital degeneracy
• Exotic Spin-Orbital Physics in Hybrid Oxides
• Exact spectral function for hole-magnon coupling in the ferromagnetic CuO${}_3$-like chain
• A possibility of high spin hole states in doped CoO${}_2$ layered systems
• Quantum versus classical polarons in a ferromagnetic CuO${}_3$-like chain