A Magnetic Model for the Ordered Double Perovskites

Abstract

We construct an effective spin model from the coupled spin-fermion problem appropriate to double perovskites of the form A_2BB'O_6. The magnetic model that emerges is reminiscent of double exchange and we illustrate this `reduction' in detail for the case of perfect B-B' structural order, i.e, no antisite disorder. We estimate the effective exchange between the magnetic B ions in terms of the electronic parameters, study the `classical' magnetic model using Monte Carlo techniques, and compare this approach to a full numerical solution of the spin-fermion problem. The agreement is reasonable, and promises a quick estimate of magnetic properties when coupled with ab initio electronic structure. The scheme generalises to the presence of antisite disorder.

12 pages latex, 10 figs

References in corpus (7)

• Structural and doping effects in the half-metallic double perovskite $A_2$CrWO${}_6$
• A new class of magnetic materials: Sr2FeMoO6 and related compounds
• Half Semimetallic Antiferromagnetism in the Sr${}_2$CrTO${}_6$ System, T=Os, Ru
• Phase diagram and influence of defects in the double perovskites
• Mean field theory for double-perovskites
• Double Exchange Models: Self Consistent Renormalisation
• Orbital ordering and magnetic structures in $\LMFO$ and $\LWFO$ double perovskites

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• Parallelized Traveling Cluster Approximation to Study Numerically Spin-Fermion Models on Large Lattices
• Theory of metallic double perovskites with spin orbit coupling and strong correlations; application to ferrimagnetic Ba2FeReO6
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• Theory of magnetism in La${}_2$NiMnO${}_6$
• Large Magnetocaloric effect and magnetic phase transitions in Nd${}_2$NiMnO${}_6$
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• Non-collinear Magnetic Order in the Double Perovskites: Double Exchange on a Geometrically Frustrated Lattice
• Magnetic order and transport in a spin-fermion model on a superlattice