Mechanism of hole propagation in the orbital compass models

Abstract

We explore the propagation of a single hole in the quantum compass model, whose nematic ground state is given by mutually decoupled antiferromagnetic chains. The compass model can be seen as the strong-coupling limit of a spinless two-band Hubbard model, which we study here using mean field theory and the variational cluster approach. Due to the symmetries of the compass model, the inherent disorder along one lattice direction turns out not to affect hole motion and doping a hole consequently does not lift the subextensive degeneracy of the nematic phase. In order to broaden and deepen understanding, we derive a generalized itinerant model and address the transition to two-dimensional Ising order. We observe coherent hole motion in both the nematic and the antiferromagnetic phases, also in the presence of quantum fluctuations away from pure Ising exchange. In addition to quantum fluctuations and interorbital hopping, three-site hopping is found to play an important role and to dominate propagation in the two-dimensional Ising limit as well as along the antiferromagnetic chains in the nematic order which forms in the compass model.

12 pages, 6 figures

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• Hole propagation in the Kitaev-Heisenberg model: From quasiparticles in quantum Neel states to non-Fermi liquid in the Kitaev phase
• Fingerprints of spin-orbital polarons and of their disorder in the photoemission spectra of doped Mott insulators with orbital degeneracy
• Frustration and Entanglement in Compass and Spin-Orbital Models
• Spin, orbital and topological order in models of strongly correlated electrons
• Green's function variational approach to orbital polarons in KCuF3
• Locally tunable disorder and entanglement in the one-dimensional plaquette orbital model
• Hole propagation in the orbital compass models
• Exotic Spin Order due to Orbital Fluctuations
• Polaron states in a CuO chain