Double exchange magnets: Spin-dynamics in the paramagnetic phase

الأصل · EN

The electronic structure of perovskite manganese oxides is investigated in terms of a Kondo lattice model with ferromagnetic Hund coupling and antiferromagnetic exchange between t₂g-spins using a finite temperature diagonalization technique. Results for the dynamic structure factor are consistent with recent neutron scattering experiments for the bilayer manganite La₁.₂Sr₁.₈Mn₂O₇. 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.