arXiv subjects

A. K. Kolezhuk

Publications and source records attributed to A. K. Kolezhuk.

39 records · Page 3Linked to original sources

arXiv1997

Quantum internal modes of solitons in 1d easy-plane antiferromagnet in strong magnetic field

In presence of a strong external magnetic field the dynamics of solitons in a one-dimensional easy-plane Heisenberg antiferromagnet exhibits a number of peculiarities. Dynamics of internal soliton degrees of freedom is essentially quantum, and they are strongly coupled to the "translational" mode of soliton movement. These peculiarities lead to considerable changes in the response functions of the system which can be detected experimentally.

cond-mat.stat-mech↗

arXiv1997

A new family of models with exact ground states connecting smoothly the S=1/2 dimer and S=1 Haldane phases of 1D spin chains

We investigate the isotropic two-leg S=1/2 ladder with general bilinear and biquadratic exchange interactions between spins on neighboring rungs, and determine the Hamiltonians which have a matrix product wavefunction as exact ground state. We demonstrate that a smooth change of parameters leads one from the S=1/2 dimer and Majumdar-Ghosh chains to the S=1 chain with biquadratic exchange. This proves that these model systems are in the same phase. We also present a new set of models of frustrated S=1/2 spin chains (including only bilinear NN and NNN interactions) whose ground states can be found exactly.

cond-mat.stat-mech↗

arXiv1996

Matrix product states approach to the Heisenberg ferrimagnetic spin chains

We propose a new version of the matrix product (MP) states approach to the description of quantum spin chains, which allows one to construct MP states with certain total spin and its z-projection. We show that previously known MP wavefunctions for integer-spin antiferromagnetic chains and ladders correspond to some particular cases of our general ansatz. Our method allows to describe systems with spontaneously broken rotational symmetry, like quantum ferrimagnetic chains whose ground state has nonzero total spin. We apply this approach to describe the ground state properties of the isotropic ferrimagnetic Heisenberg chain with alternating spins 1 and 1/2 and compare our variational results with the high-precision numerical data obtained by means of the quantum Monte Carlo (QMC) method. For both the ground state energy and the correlation functions we obtain very good agreement between the variational results and the QMC data.

cond-mat↗