Double exchange and orbital correlations in electron-doped manganites

Abstract

A double exchange model for degenerate $e_g$ orbitals with intra- and inter-orbital interactions has been studied for the electron doped manganites A${}_{1-x}$B${}_x$MnO${}_3$ ($x>0.5$). We show that such a model reproduces the observed phase diagram and orbital ordering in the intermediate bandwidth regime and the Jahn-Teller effect, considered to be crucial for the region $x<0.5$, does not play a major role in this region. Brink and Khomskii have already pointed this out and stressed the relevance of the anistropic hopping across the degenerate $e_g$ orbitals in the infinite Hund's coupling limit. From a more realistic calculation with finite Hund's coupling, we show that inclusion of interactions stabilizes the C-phase, the antiferromagnetic metallic A-phase moves closer to $x=0.5$ while the ferromagnetic phase shrinks. This is in agreement with the recent observations of Kajimoto et. al. and Akimoto et. al.

text 9 pages, 5 figures

References in corpus (1)

• Colossal Magnetoresistant Materials: The Key Role of Phase Separation

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