RT Journal Article
T1 Variational mean-field approach to the double-exchange model
A1 Alonso, J. L.
A1 Fernández Pérez, Luis Antonio
A1 Guinea, F.
A1 Laliena, V.
A1 Martín Mayor, Víctor
AB It has been recently shown that the double exchange Hamiltonian, with weak antiferromagnetic interactions, has a richer variety of first- and second-order transitions than previously anticipated, and that such transitions are consistent with the magnetic properties of manganites. Here we present a thorough discussion of the variational mean-field approach that leads to these results. We also show that the effect of the Berry phase turns out to be crucial to produce first-order paramagnetic-ferromagnetic transitions near half filling with transition temperatures compatible with the experimental situation. The computation relies on two crucial facts: the use of a mean-field ansatz that retains the complexity of a system of electrons with off-diagonal disorder, not fully taken into account by the mean-field techniques, and the small but significant antiferromagnetic superexchange interaction between the localized spins.
PB American Physical Society
SN 1098-0121
YR 2011
FD 2011-02-01
LK https://hdl.handle.net/20.500.14352/42572
UL https://hdl.handle.net/20.500.14352/42572
LA eng
NO © 2001 The American Physical Society. We are thankful for helpful conversations to L. Brey, J. Fontcuberta, G. Gómez-Santos, C. Simon, J. M. de Teresa, and especially to R. Ibarra and V. S. Amaral. V.M.-M. was partially supported by MEC. We acknowledge financial support from Grant Nos. PB96-0875, AEN97-1680, AEN97- 1693, AEN97-1708, AEN99-0990 (MEC, Spain), and (07N/0045/98) (C. Madrid).
NO MEC
NO Comunidad de Madrid
DS Docta Complutense
RD 25 abr 2025