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Abstract:
We have analyzed different correlation functions in a realistic
spin-orbital model for half-doped manganites. Using a
finite-temperature diagonalization technique the CE phase was found in
the charge-ordered phase in the case of small antiferromagnetic
interactions between t(2g) electrons. It is shown that the ingredient
responsible for stabilization of the CE-type spin and orbital-ordered
state is the cooperative Jahn-Teller (JT) interaction between
next-nearest Mn+3 neighbors mediated by the breathing mode distortion
of Mn+4 octahedra and displacements of Mn+4 ions. The topological phase
factor in the Mn-Mn hopping leading to gap formation in one-dimensional
models for the CE phase as well as the nearest neighbor JT coupling are
not able to produce the zigzag chains typical for the CE phase in our
model.
