Relevance of cooperative lattice effects and stress fields in phase-separation theories for CMR manganites.
Previous theoretical investigations of colossal magnetoresistance (CMR) materials explain this effect using a "clustered" state with preformed ferromagnetic islands that rapidly align their moments with increasing external magnetic fields. While qualitatively successful, explicit calculations indicate drastically different typical resistivity values in two- and three-dimensional lattices, contrary to experimental observations. This conceptual bottleneck in the phase-separated CMR scenario is resolved here considering the cooperative nature of the Mn-oxide lattice distortions. This effectively induces power-law correlations in the quenched disorder used in toy models with phase competition. When these effects are incorporated, resistor-network calculations reveal very similar results in two and three dimensions, qualitatively modifying previous scenarios and solving the puzzle.
Burgy
Jan
J
National High Magnetic Field Lab and Department of Physics, Florida State University, Tallahassee, Florida 32306, USA.
Moreo
Adriana
A
Dagotto
Elbio
E