Double exchange magnets: Spin-dynamics in the paramagnetic phase
arXiv:cond-mat/9708007 · doi:10.1103/PhysRevB.59.R14149
Abstract
The electronic structure of perovskite manganese oxides is investigated in terms of a Kondo lattice model with ferromagnetic Hund coupling and antiferromagnetic exchange between $t_{2g}$-spins using a finite temperature diagonalization technique. Results for the dynamic structure factor are consistent with recent neutron scattering experiments for the bilayer manganite La$_{1.2}$Sr$_{1.8}$Mn$_2$O$_7$ . The susceptibility shows Curie-Weiss behaviour and is used to derive a phase diagram. In the paramagnetic phase carriers are characterized as ferromagnetic polarons in an antiferromagnetic spin liquid.
Revtex, 4 pages with 5 postscript figures included