Frustration and Entanglement in Compass and Spin-Orbital Models

Abstract

We review the consequences of intrinsic frustration of the orbital superexchange and of spin-orbital entanglement. While Heisenberg perturbing interactions remove frustration in the compass model, the lowest columnar excitations are robust in the nanoscopic compass clusters and might be used for quantum computations. Entangled spin-orbital states determine the ground states in some cases, while in others concern excited states and lead to measurable consequences, as in the $R$VO${}_3$ perovskites. On-site entanglement for strong spin-orbit coupling generates the frustrated Kitaev-Heisenberg model with a rich magnetic phase diagram on the honeycomb lattice. Frustration is here reflected in hole propagation which changes from coherent in an antiferromagnet via hidden quasiparticles in zigzag and stripe phases to entirely incoherent one in the Kitaev spin liquid.

8 pages, 5 figures, invited talk at PM'14 Conference, Poznan, June 2014

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Cited by in corpus (5)

• Spin-orbital order in undoped manganite LaMnO3 at finite temperature
• Green's function variational approach to orbital polarons in KCuF3
• Charge transfer model for the electronic structure of layered ruthenates
• Hole propagation in the orbital compass models
• Quantum phase transitions in the Kitaev--Heisenberg model on a single hexagon