We propose to engineer time-reversal-invariant topological insulators in two-dimensional crystals... more We propose to engineer time-reversal-invariant topological insulators in two-dimensional crystals of transition-metal dichalcogenides (TMDCs). We note that, at low doping, semiconducting TMDCs under shear strain will develop spin-polarized Landau levels residing in different valleys. We argue that gaps between Landau levels in the range of 10-100 K are within experimental reach. In addition, we point out that a superlattice arising from a moiré pattern can lead to topologically nontrivial subbands. As a result, the edge transport becomes quantized, which can be probed in multiterminal devices made using strained 2D crystals and/or heterostructures. The strong d character of valence and conduction bands may also allow for the investigation of the effects of electron correlations on the topological phases.
The delicate interplay between plasmonic excitations and interband transitions in noble metals is... more The delicate interplay between plasmonic excitations and interband transitions in noble metals is described by means of ab initio calculations and a simple model in which the conduction electron plasmon is coupled to the continuum of electron-hole pairs. Band structure effects, specially the energy at which the excitation of the d-like bands takes place, determine the existence of a subthreshold plasmonic mode, which manifests itself in Ag as a sharp resonance at 3.8 eV. However, such a resonance is not observed in the other noble metals. Here, this different behavior is also analyzed and an explanation is provided.
The dissipation induced by a metallic gate on the low-energy properties of interacting 1D electro... more The dissipation induced by a metallic gate on the low-energy properties of interacting 1D electron liquids is studied. As function of the distance to the gate, or the electron density in the wire, the system undergoes a quantum phase transition from the Tomonaga-Luttinger liquid state to two kinds of dissipative phases, one of them with a finite spatial correlation length. We also define a dual model, which describes an attractive one dimensional metal with a Josephson coupling to a dirty metallic lead.
We show that a two-dimensional (2D) array of 1D interacting boson tubes has a deconfinement trans... more We show that a two-dimensional (2D) array of 1D interacting boson tubes has a deconfinement transition between a 1D Mott insulator and a 3D superfluid for commensurate fillings and a dimensional crossover for the incommensurate case. We determine the phase diagram and excitations of this system and discuss the consequences for Bose condensates loaded in 2D optical lattices.
We study the phase diagram of one dimensional spin-1 2 fermionic cold atoms. The two "spin" speci... more We study the phase diagram of one dimensional spin-1 2 fermionic cold atoms. The two "spin" species can have different hopping or mass. The phase diagram at equal densities of the species is found to be very rich, containing Mott insulators and superfluids. We also briefly discuss coupling 1D systems together, and some experimental signatures of these phases. In particular, we compute the spin structure factor for small momentum, which should allow the spin gap to be detected.
Journal of Statistical Mechanics: Theory and Experiment, 2013
We study the entanglement entropy scaling of the XXZ chain. While in the critical XY phase of the... more We study the entanglement entropy scaling of the XXZ chain. While in the critical XY phase of the XXZ chain the entanglement entropy scales logarithmically with a coefficient that is determined by the associated conformal field theory, at the ferromagnetic point, however, the system is not conformally invariant yet the entanglement entropy still scales logarithmically albeit with a different coefficient. We investigate how such an nontrivial scaling at the ferromagnetic point influences the estimation of the central charge c in the critical XY phase. In particular we use the entanglement scaling of the finite or infinite system, as well as the finite-size scaling of the ground state energy to estimate the value of c. In addition, the spin-wave velocity and the scaling dimension are also estimated. We show that in all methods the evaluations are influenced by the nearby ferromagnetic point and result in crossover behavior. Finally we discuss how to determine whether the central charge estimation is strongly influenced by the crossover behavior and how to properly evaluate the central charge.
We investigate a one dimensional system of cold bosonic atoms in an optical lattice subjected to ... more We investigate a one dimensional system of cold bosonic atoms in an optical lattice subjected to a time dependent periodic potential. We study the dynamic structure factor and the excitation spectrum in different regimes: superfluid and Mott insulator. In particular the strong interactions gives rise to a continuum of excitations in the superfluid phase. We discuss the application to recent
We study the local moment formation and the Kondo effect at single-atom vacancies in Graphene. We... more We study the local moment formation and the Kondo effect at single-atom vacancies in Graphene. We develop a model accounting for the vacancy reconstruction as well as non-planarity effects induced by strain and/or temperature. Thus, we find that the dangling σ orbital localized at the vacancy is allowed to strongly hybridize with the π-band since the scattering with the vacancy turns the hybridization into singular function of the energy (∼ [| | ln 2 /D] −1 , D ∼ the bandwidth). This leads to several new types of impurity phases, which control the magnitude of the vacancy magnetic moment and the possibility of Kondo effect depending on the strength of the local Coulomb interactions, the Hund's rule coupling, the doping level, and the degree of particle-symmetry breaking.
We propose to engineer time-reversal-invariant topological insulators in two-dimensional crystals... more We propose to engineer time-reversal-invariant topological insulators in two-dimensional crystals of transition-metal dichalcogenides (TMDCs). We note that, at low doping, semiconducting TMDCs under shear strain will develop spin-polarized Landau levels residing in different valleys. We argue that gaps between Landau levels in the range of 10-100 K are within experimental reach. In addition, we point out that a superlattice arising from a moiré pattern can lead to topologically nontrivial subbands. As a result, the edge transport becomes quantized, which can be probed in multiterminal devices made using strained 2D crystals and/or heterostructures. The strong d character of valence and conduction bands may also allow for the investigation of the effects of electron correlations on the topological phases.
The delicate interplay between plasmonic excitations and interband transitions in noble metals is... more The delicate interplay between plasmonic excitations and interband transitions in noble metals is described by means of ab initio calculations and a simple model in which the conduction electron plasmon is coupled to the continuum of electron-hole pairs. Band structure effects, specially the energy at which the excitation of the d-like bands takes place, determine the existence of a subthreshold plasmonic mode, which manifests itself in Ag as a sharp resonance at 3.8 eV. However, such a resonance is not observed in the other noble metals. Here, this different behavior is also analyzed and an explanation is provided.
The dissipation induced by a metallic gate on the low-energy properties of interacting 1D electro... more The dissipation induced by a metallic gate on the low-energy properties of interacting 1D electron liquids is studied. As function of the distance to the gate, or the electron density in the wire, the system undergoes a quantum phase transition from the Tomonaga-Luttinger liquid state to two kinds of dissipative phases, one of them with a finite spatial correlation length. We also define a dual model, which describes an attractive one dimensional metal with a Josephson coupling to a dirty metallic lead.
We show that a two-dimensional (2D) array of 1D interacting boson tubes has a deconfinement trans... more We show that a two-dimensional (2D) array of 1D interacting boson tubes has a deconfinement transition between a 1D Mott insulator and a 3D superfluid for commensurate fillings and a dimensional crossover for the incommensurate case. We determine the phase diagram and excitations of this system and discuss the consequences for Bose condensates loaded in 2D optical lattices.
We study the phase diagram of one dimensional spin-1 2 fermionic cold atoms. The two "spin" speci... more We study the phase diagram of one dimensional spin-1 2 fermionic cold atoms. The two "spin" species can have different hopping or mass. The phase diagram at equal densities of the species is found to be very rich, containing Mott insulators and superfluids. We also briefly discuss coupling 1D systems together, and some experimental signatures of these phases. In particular, we compute the spin structure factor for small momentum, which should allow the spin gap to be detected.
Journal of Statistical Mechanics: Theory and Experiment, 2013
We study the entanglement entropy scaling of the XXZ chain. While in the critical XY phase of the... more We study the entanglement entropy scaling of the XXZ chain. While in the critical XY phase of the XXZ chain the entanglement entropy scales logarithmically with a coefficient that is determined by the associated conformal field theory, at the ferromagnetic point, however, the system is not conformally invariant yet the entanglement entropy still scales logarithmically albeit with a different coefficient. We investigate how such an nontrivial scaling at the ferromagnetic point influences the estimation of the central charge c in the critical XY phase. In particular we use the entanglement scaling of the finite or infinite system, as well as the finite-size scaling of the ground state energy to estimate the value of c. In addition, the spin-wave velocity and the scaling dimension are also estimated. We show that in all methods the evaluations are influenced by the nearby ferromagnetic point and result in crossover behavior. Finally we discuss how to determine whether the central charge estimation is strongly influenced by the crossover behavior and how to properly evaluate the central charge.
We investigate a one dimensional system of cold bosonic atoms in an optical lattice subjected to ... more We investigate a one dimensional system of cold bosonic atoms in an optical lattice subjected to a time dependent periodic potential. We study the dynamic structure factor and the excitation spectrum in different regimes: superfluid and Mott insulator. In particular the strong interactions gives rise to a continuum of excitations in the superfluid phase. We discuss the application to recent
We study the local moment formation and the Kondo effect at single-atom vacancies in Graphene. We... more We study the local moment formation and the Kondo effect at single-atom vacancies in Graphene. We develop a model accounting for the vacancy reconstruction as well as non-planarity effects induced by strain and/or temperature. Thus, we find that the dangling σ orbital localized at the vacancy is allowed to strongly hybridize with the π-band since the scattering with the vacancy turns the hybridization into singular function of the energy (∼ [| | ln 2 /D] −1 , D ∼ the bandwidth). This leads to several new types of impurity phases, which control the magnitude of the vacancy magnetic moment and the possibility of Kondo effect depending on the strength of the local Coulomb interactions, the Hund's rule coupling, the doping level, and the degree of particle-symmetry breaking.
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Papers by M. Cazalilla