0000000001142902

AUTHOR

Andrea Di Ciolo

showing 2 related works from this author

Quantum gap and spin-wave excitations in the Kitaev model on a triangular lattice

2017

We study the effects of quantum fluctuations on the dynamical generation of a gap and on the evolution of the spin-wave spectra of a frustrated magnet on a triangular lattice with bond-dependent Ising couplings, analog of the Kitaev honeycomb model. The quantum fluctuations lift the subextensive degeneracy of the classical ground-state manifold by a quantum order-by-disorder mechanism. Nearest-neighbor chains remain decoupled and the surviving discrete degeneracy of the ground state is protected by a hidden model symmetry. We show how the four-spin interaction, emergent from the fluctuations, generates a spin gap shifting the nodal lines of the linear spin-wave spectrum to finite energies.

Frustrated magnetismFOS: Physical sciencesBond-dependent Ising couplingsQuantum fluctuations01 natural sciencesTriangular lattice010305 fluids & plasmasCondensed Matter - Strongly Correlated ElectronsSpin waveQuantum mechanics0103 physical sciencesSpin gapHexagonal latticeElectrical and Electronic Engineering010306 general physicsQuantumQuantum fluctuationSpin-½PhysicsCondensed matter physicsStrongly Correlated Electrons (cond-mat.str-el)Condensed Matter PhysicsElectronic Optical and Magnetic MaterialsBond-dependent Ising couplings; Frustrated magnetism; Linear spin-wave spectrum; Quantum fluctuations; Spin gap; Triangular lattice;Ising modelGround stateDegeneracy (mathematics)Linear spin-wave spectrum
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Single-particle properties of the Hubbard model in a novel three-pole approximation

2017

We study the 2D Hubbard model using the Composite Operator Method within a novel three-pole approximation. Motivated by the long-standing experimental puzzle of the single-particle properties of the underdoped cuprates, we include in the operatorial basis, together with the usual Hubbard operators, a field describing the electronic transitions dressed by the nearest-neighbor spin fluctuations, which play a crucial role in the unconventional behavior of the Fermi surface and of the electronic dispersion. Then, we adopt this approximation to study the single-particle properties in the strong coupling regime and find an unexpected behavior of the van Hove singularity that can be seen as a prec…

Hubbard modelSingle-particle propertiesField (physics)Hubbard modelThree-pole approximationVan Hove singularityFOS: Physical sciences02 engineering and technology01 natural sciencesCondensed Matter - Strongly Correlated ElectronsQuantum mechanicsCondensed Matter::Superconductivity0103 physical sciencesCuprateElectrical and Electronic Engineering010306 general physicsSpin-½PhysicsCondensed matter physicsStrongly Correlated Electrons (cond-mat.str-el)Strongly correlated electron systemsFermi surface021001 nanoscience & nanotechnologyCondensed Matter PhysicsComposite Operator MethodElectronic Optical and Magnetic MaterialsComposite Operator Method; Hubbard model; Operatorial approach; Single-particle properties; Strongly correlated electron systems; Three-pole approximation;Operatorial approachStrongly correlated materialCondensed Matter::Strongly Correlated Electrons0210 nano-technologyPseudogap
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