Phase diagram of the bosonic double-exchange model



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Alonso, J. L. and Cruz, A. and Fernández Pérez, Luis Antonio and JIménez, S. and Martín Mayor, Víctor and Ruiz-Lorenzo, J. J. and Tarancón, A. (2005) Phase diagram of the bosonic double-exchange model. Physical review B, 71 (1). ISSN 1098-0121

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The phase diagram of the simplest approximation to double-exchange systems, the bosonic double-exchange model with antiferromagnetic (AFM) superexchange coupling, is fully worked out by means of Monte Carlo simulations, large-N expansions, and variational mean-field calculations. We find a rich phase diagram, with no first-order phase transitions. The most surprising finding is the existence of a segmentlike ordered phase at low temperature for intermediate AFM coupling which cannot be detected in neutron-scattering experiments. This is signaled by a maximum (a cusp) in the specific heat. Below the phase transition, only short-range ordering would be found in neutron scattering. Researchers looking for a quantum critical point in manganites should be wary of this possibility. Finite-size scaling estimates of critical exponents are presented, although large scaling corrections are present in the reachable lattice sizes.

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© 2005 The American Physical Society. It is a pleasure to thank F. Guinea for useful conversation at the beginning of this work. We have maintained interesting discussions with A. Pelissetto regarding the large-N approximation. This work has been partially supported through research contracts FPA2001-1813, FPA2000-0956, BFM2001-0718, BFM2003-8532, PB98-0842 sMCyTd and HPRN-CT-2002-00307 sEUd. We have used the PentiumIV cluster RTN3 at the Universidad de Zaragoza for the simulations. S.J. was supported by DGA.

Uncontrolled Keywords:Antiferromagnetic RP(2) model; Ferromagnetic phases; 3 dimensions; Renormalization-group; Ising-model; La(1-x)Sr(x)MnO(3); Transitions; Heisenberg; Crystals; Magnets.
Subjects:Sciences > Physics
Sciences > Physics > Physics-Mathematical models
ID Code:38466
Deposited On:22 Jul 2016 11:50
Last Modified:22 Jul 2016 11:50

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