arXiv subjects

Yusuke Kato

Publications and source records attributed to Yusuke Kato.

96 records · Page 6Linked to original sources

arXiv1996

Partially Solvable Anisotropic t-J Model with Long-Range Interactions

A new anisotropic t-J model in one dimension is proposed which has long-range hopping and exchange. This t-J model is only partially solvable in contrast to known integrable models with long-range interaction. In the high-density limit the model reduces to the XXZ chain with the long-range exchange. Some exact eigenfunctions are shown to be of Jastrow-type if certain conditions for an anisotropy parameter are satisfied. The ground state as well as the excitation spectrum for various cases of the anisotropy parameter and filling are derived numerically. It is found that the Jastrow-type wave function is an excellent trial function for any value of the anisotropy parameter.

cond-mat↗

arXiv1996

Fractional Exclusion Statistics for the t-J Model

We construct thermodynamics of the one-dimensional supersymmetric {\it t-J} model with the $ 1/\sin^2$ interaction and hopping. The thermodynamics is described exactly in terms of free spinons and holons obeying Haldane's fractional exclusion statistics at all temperatures. Moreover, at low temperatures the semionic spinons and holons decouple resulting in the spin-charge separation in thermodynamic properties. We obtain explicit results for the spin and charge susceptibilities and specific heat, and interpret them in terms of the fractional exclusion statistics. Extension to the multi-component {\it t-J} model shows that the excitations obey either fractional statistics for g-ons with partial polarization of components, or the parafermionic one without polarization.

cond-mat↗

arXiv1996

Fractional Exclusion Statistics for the Multicomponent Sutherland Model

We show by microscopic calculation that thermodynamics of the multicomponent Sutherland model is equivalent to that of a free particle system with fractional exclusion statistics at all temperatures. The parameters for exclusion statistics are given by the strength of the repulsive interaction, and have both intra- and inter-species components. We also show that low temperature properties of the system are described in terms of free fractional particles without the statistical parameters for different species. The effective exclusion statistics for intra-species at low temperatures depend on polarization of the system.

cond-mat↗

arXiv1995

Spin-Charge Separation at Finite Temperature in the Supersymmetric t-J Model with Long-Range Interactions

Thermodynamics is derived rigorously for the 1D supersymmetric {\it t-J} model and its SU($K,1$) generalization with inverse-square exchange. The system at low temperature is described in terms of spinons, antispinons, holons and antiholons obeying fractional statistics. They are all free and make the spin susceptibility independent of electron density, and the charge susceptibility independent of magnetization. Thermal spin excitations responsible for the entropy of the SU($K,1$) model are ascribed to free para-fermions of order $K-1$.

cond-mat↗

arXiv1994

Exact Solution of the Sutherland Model with arbitrary symmetry

An elementary theory is presented for solving the Sutherland model with arbitrary internal symmetry such as SU($ν$) or a supersymmetry SU($ν, μ$). The ground state wave function and all the energy levels are derived. One starts with solving a variant of the model with distinguishable particles, and then (anti)symmetrizes the solution. The theory is also applied to various lattice versions of the model. It is proved that the Gutzwiller-type wave function is not only an eigenstate of the supersymmetric \it t-J \rm model, but is indeed the ground state.

cond-mat↗

arXiv1994

Numerical Study of the $S=1$ Antiferrromagnetic Spin Chain with Bond Alternation

We study the $S=1$ quantum spin chain with bond alternation ${\cal H}=\sum _i (1-(-1)^iδ)\vect{S}_i\cdot \vect{S}_{i+1}$ by the density matrix renormalization group method recently proposed by Steven R. White (\PRL{69}{3844}{1993}). We find a massless point at $δ_c =0.25 \pm 0.01$. We also find the edge states in the region $δ<δ_c$ under the open boundary condition, which disappear in the region $δ>δ_{c}$. At the massless point, the spin wave velocity $v_s$ is $3.66 \pm 0.10$ and the central charge $c$ is $1.0\pm 0.15$. Our results indicate that a continuous phase transition occurs at the massless point $δ=δ_c $ accompanying breaking of the hidden $Z_2\times Z_2$ symmetry.

cond-mat↗