94 citations · 511 across the 15 of their papers we have counts for
15 papers
Phase diagram of S=1/2 two-leg XXZ spin ladder systems
K. Hijii, A. Kitazawa, K. Nomura
We investigate the ground state phase diagram of the S=1/2 two-leg spin ladder system with an isotropic interchain coupling. In this model, there is the Berezinskii-Kosterlit…
BKT transition and level spectroscopy
Kiyohide Nomura, Atsuhiro Kitazawa
Berezinskii-Kosterlitz-Thouless (BKT) transition is one of the instability mechanisms for the Tomonaga-Luttinger liquid. But in the BKT transition, there are logarithmic-correction…
Magnetization-plateau state of the S=3/2 spin chain with single ion anisotropy
Atsuhiro Kitazawa, Kiyomi Okamoto
We reexamine the numerical study of the magnetized state of the S=3/2 spin chain with single ion anisotropy D(> 0) for the magnetization M=M_{S}/3, where M_{S} is the saturation ma…
Breakdown of the magnetization plateau of the S=1/2 ferromagnetic-ferromagnetic-antiferromagnetic trimerized spin chain with anisotropy
Atsuhiro Kitazawa, Kiyomi Okamoto
We study the breakdown of the magnetization plateau at the magnetization M=M_{S}/3 (M_{S} is the saturation magnetization) of the S=1/2 anisotropic spin chain with ferromagnetic-fe…
Quantum Phase Transition of S=1/2 Trimerized XXZ Spin Chain in Magnetic Field
Kiyomi Okamoto, Atsuhiro Kitazawa
We study the magnetization plateau at a third of the saturation magnetization of the S=1/2 trimerized XXZ spin chain at T=0. The appearance of the plateau depends on the values of…
Spin-Gap Phases in Tomonaga-Luttinger Liquids
Masaaki Nakamura, Atsuhiro Kitazawa, Kiyohide Nomura
We give the details of the analysis for critical properties of spin-gap phases in one-dimensional lattice electron models. In the Tomonaga-Luttinger (TL) liquid theory, the spin-ga…
Bifurcation at the c=3/2 Takhtajan-Babujian point to the c=1 critical lines
Atsuhiro Kitazawa, Kiyohide Nomura
We study the S=1 quantum spin chains with bilinear, biquadratic, plus bond alternation in the vicinity of the S=1 Takhtajan-Babujian model. Transition line between the Haldane and…
Magnetization plateau and quantum phase transition of the S=1/2 trimerized XXZ spin chain
Kiyomi Okamoto, Atsuhiro Kitazawa
We study the plateau of the magnetization curve at ( is the saturation magnetization) of the trimerized spin chain. By examining the leve…
symmetry of the BKT transition and twisted boundary conditio n
Kiyohide Nomura, Atsuhiro Kitazawa
Berezinskii-Kosterlitz-Thouless (BKT) transition, the transition of the 2D sine-Gordon model, plays an important role in the low dimensional physics. We relate the operator content…
Renormalization group analysis of the spin-gap phase in the one-dimensional t-J model
Masaaki Nakamura, Kiyohide Nomura, Atsuhiro Kitazawa
We study the spin-gap phase in the one-dimensional t-J model, assuming that it is caused by the backward scattering process. Based on the renormalization group analysis and symmetr…
Phase Diagrams of S=3/2, 2 XXZ Spin Chains with Bond-Alternation
Atsuhiro Kitazawa, Kiyohide Nomura
We study the phase diagram of S=3/2 and S=2 bond-alternating spin chains numerically. In previous papers, the phase diagram of S=1 XXZ spin chain with bond-alternation was shown to…
Phase Diagram of S=1 Bond-Alternating XXZ Chains Reflecting the Hidden Z_2\times Z_2 Symmetry
Atsuhiro Kitazawa, Kiyohide Nomura
The phase diagram of the spin-1 bond-alternating XXZ chain is studied numerically. This model is appropriate to study the VBS picture and the hidden Z_2\times Z_2 symmetry concerni…
Twist Boundary Conditions of Quantum Spin Chains near the Gaussian Fixed Points
A. Kitazawa
Duality transformation, which relates a high-temperature phase to a low-temperature one, is used exactly to determine the critical point for several models (2D Ising, Potts, Ashkin…
Level spectroscopy II - application to the Gaussian model -
Kiyohide Nomura, Atsuhiro Kitazawa
It was a difficult problem to determine the Gaussian fixed line from the numerical data, because close to the Berezinskii-Kosterlitz-Thouless multicritical point the divergence of…
Phase Diagram of Bond-Alternating XXZ chains
Atsuhiro Kitazawa, Kiyohide Nomura, Kiyomi Okamoto
The phase transitions between the XY, the dimer and the Haldane phases of the spin-1 bond-alternating XXZ chain are studied by the numerical diagonalization. We determine the phase…