We consider the effective model of $H=-J_{1}\sum_{}\mathbf{S}_{i}\cdot \mathbf{S}_{j}-J_{2}\sum_{}(\mathbf{S}_{i}\cdot \mathbf{S}_{j}) ^{2}$ , describing the Mott insulating phase with odd number of spin-1 bosons in optical lattices ( $J_{2}>J_{1}>0$ ). In terms of an SU(3) boson representation, a valence bond mean field theory is developed. In 1D, a \textit{first-order} quantum phase transition from a spin singlet to a spin nematic phase with \textit{gapful} excitations is identified at $ J_{1}/J_{2}=0.19833$, while on a 2D square lattice a spin nematic ordered phase with gapless excitations prevails. In both 1D and 2D cases, we predict that the spin structure factor displays dominant antiferromagnetic fluctuations, while the quadrupole structure factor exhibits strong ferroquadrupolar correlations.We consider the effective model of $H=-J_{1}\sum_{}\mathbf{S}_{i}\cdot \mathbf{S}_{j}-J_{2}\sum_{}(\mathbf{S}_{i}\cdot \mathbf{S}_{j}) ^{2}$, describing the Mott insulating phase with odd number of spin-1 bosons in optical lattices ($J_{2}>J_{1}>0$). In terms of an SU(3) boson representation, a valence bond mean field theory is developed. In 1D, a \textit{first-order} quantum phase transition from a spin singlet to a spin nematic phase with \textit{gapful} excitations is identified at $ J_{1}/J_{2}=0.19833$, while on a 2D square lattice a spin nematic ordered phase with gapless excitations prevails. In both 1D and 2D cases, we predict that the spin structure factor displays dominant antiferromagnetic fluctuations, while the quadrupole structure factor exhibits strong ferroquadrupolar correlations.

arXiv:cond-mat/0507158Jul 7, 20050 citations

Elementary excitations for the integrable spin-SHeisenberg chain with an impurity spin

Yosuke Morita, Sei-ichiro Suga, A. Okiji

Elementary excitations for the integrable spin-S antiferromagnetic Heisenberg chain with an impurity spin are investigated by using the Bethe ansatz solution. Dressed holes are introduced in order to describe the elementary excitation. The characteristic energy dependence of the spectral density for the elementary excitation at zero temperature is discussed in connection with behaviour patterns of physical quantities. We extend our calculation for the elementary excitation to the case of finite temperatures, applying the method developed by Yang and Yang for one-dimensional interacting boson systems. At finite temperatures, in the case where , the spectral density shows a divergence property at zero excitation energy irrespective of the temperature, whereas in the case where , the peak structure develops in the low-energy region as the temperature is decreased.Elementary excitations for the integrable spin-S antiferromagnetic Heisenberg chain with an impurity spin are investigated by using the Bethe ansatz solution. Dressed holes are introduced in order to describe the elementary excitation. The characteristic energy dependence of the spectral density for the elementary excitation at zero temperature is discussed in connection with behaviour patterns of physical quantities. We extend our calculation for the elementary excitation to the case of finite temperatures, applying the method developed by Yang and Yang for one-dimensional interacting boson systems. At finite temperatures, in the case where , the spectral density shows a divergence property at zero excitation energy irrespective of the temperature, whereas in the case where , the peak structure develops in the low-energy region as the temperature is decreased.

Journal of Physics Condensed MatterMar 11, 19962 citations

Dynamics of spin-1 bosons in an optical lattice

Khan W. Mahmud, Eite Tiesinga

Bulletin of the American Physical SocietyMar 18, 20130 citations

Spinfull bosons in an optical lattice

Sara Bergkvist, Ian P. McCulloch, Anders Rosengren

Bulletin of the American Physical SocietyMar 16, 20060 citations

Excitation spectrum of the homogeneous spin liquid

R. Eder

We discuss the excitation spectrum of a disordered, isotropic, and translationally invariant spin state in the two-dimensional Heisenberg antiferromagnet. The starting point is the nearest-neighbor resonating-valence-bond state which plays the role of the vacuum of the theory, in a similar sense as the N\'eel state is the vacuum for antiferromagnetic spin-wave theory. We discuss the elementary excitations of this state and show that these are not Fermionic spin-1/2 ``spinons'' but spin-1 excited dimers which must be modeled by bond bosons. We derive an effective Hamiltonian describing the excited dimers which is formally analogous to spin-wave theory. Condensation of the bond bosons at zero temperature into the state with momentum $(\ensuremath{\pi},\ensuremath{\pi})$ is shown to be equivalent to antiferromagnetic ordering. The latter is a key ingredient for a microscopic interpretation of Zhang's SO(5) theory of cuprate superconductivity.We discuss the excitation spectrum of a disordered, isotropic, and translationally invariant spin state in the two-dimensional Heisenberg antiferromagnet. The starting point is the nearest-neighbor resonating-valence-bond state which plays the role of the vacuum of the theory, in a similar sense as the N\'eel state is the vacuum for antiferromagnetic spin-wave theory. We discuss the elementary excitations of this state and show that these are not Fermionic spin-1/2 ``spinons'' but spin-1 excited dimers which must be modeled by bond bosons. We derive an effective Hamiltonian describing the excited dimers which is formally analogous to spin-wave theory. Condensation of the bond bosons at zero temperature into the state with momentum $(\ensuremath{\pi},\ensuremath{\pi})$ is shown to be equivalent to antiferromagnetic ordering. The latter is a key ingredient for a microscopic interpretation of Zhang's SO(5) theory of cuprate superconductivity.

arXiv:cond-mat/9810216Physical review. B, Condensed matterJun 1, 19995 citations

We consider the effective model of

H=-J_{1}\sum_{}\mathbf{S}_{i}\cdot \mathbf{S}_{j}-J_{2}\sum_{}(\mathbf{S}_{i}\cdot \mathbf{S}_{j}) ^{2}

, describing the Mott insulating phase with odd number of spin-1 bosons in optical lattices (

J_{2}>J_{1}>0

). In terms of an SU(3) boson representation, a valence bond mean field theory is developed. In 1D, a \textit{first-order} quantum phase transition from a spin singlet to a spin nematic phase with \textit{gapful} excitations is identified at $ J_{1}/J_{2}=0.19833$, while on a 2D square lattice a spin nematic ordered phase with gapless excitations prevails. In both 1D and 2D cases, we predict that the spin structure factor displays dominant antiferromagnetic fluctuations, while the quadrupole structure factor exhibits strong ferroquadrupolar correlations.