paper

Charge and orbital order in half-doped manganites

arXiv:cond-mat/9910253 · doi:10.1103/PhysRevLett.83.5118

Abstract

An explanation is given for the charge order, orbital order and insulating state observed in half-doped manganese oxides, such as NdSrMnO. The competition between the kinetic energy of the electrons and the magnetic exchange energy drives the formation of effectively one-dimensional ferromagnetic zig-zag chains. Due to a topological phase factor in the hopping, the chains are intrinsically insulating and orbital-ordered. Most surprisingly, the strong Coulomb interaction between electrons on the same Mn-ion leads to the experimentally observed charge ordering. For doping less than 1/2 the system is unstable towards phase separation into a ferromagnetic metallic and charge-ordered insulating phase.

To appear in Phys. Rev. Lett., 4 pages, 4 figures

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