6533b839fe1ef96bd12a5c76
RESEARCH PRODUCT
Quantum order by disorder in the Kitaev model on a triangular lattice
George JackeliGeorge JackeliAdolfo Avellasubject
PhysicsStrongly Correlated Electrons (cond-mat.str-el)Topological degeneracyFOS: Physical sciencesCondensed Matter PhysicsElectronic Optical and Magnetic MaterialsCondensed Matter Physics; Electronic Optical and Magnetic MaterialsCondensed Matter - Strongly Correlated ElectronsQuantum mechanicsElectronicHexagonal latticeOptical and Magnetic MaterialsGround stateDegeneracy (mathematics)QuantumQuantum fluctuationCluster expansionSpin-½description
We identify and discuss the ground state of a quantum magnet on a triangular lattice with bond-dependent Ising-type spin couplings, that is, a triangular analog of the Kitaev honeycomb model. The classical ground-state manifold of the model is spanned by decoupled Ising-type chains, and its accidental degeneracy is due to the frustrated nature of the anisotropic spin couplings. We show how this subextensive degeneracy is lifted by a quantum order-by-disorder mechanism and study the quantum selection of the ground state by treating short-wavelength fluctuations within the linked cluster expansion and by using the complementary spin-wave theory. We find that quantum fluctuations couple next-nearest-neighbor chains through an emergent four-spin interaction, while nearest-neighbor chains remain decoupled. The remaining discrete degeneracy of the ground state is shown to be protected by a hidden symmetry of the model.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 2015-01-01 | Physical Review B |