Antiferromagnetic Heisenberg integer-spin chains are characterized by a spin-liquid ground state with no long-range order, due to the relevance of quantum fluctuations. Spin anisotropy, however, freezes quantum fluctuations, and the system is magnetized in the presence of a sufficiently large easy-axis anisotropy. We numerically investigate the case S=1, by means of the density-matrix renormalization group, and find that the freezing of the spin liquid into a Néel spin solid, with increasing easy-axis anisotropy, is a continuous quantum phase transition. Numerical evidence indicates that the transition is not in the two-dimensional Ising universality class.Antiferromagnetic Heisenberg integer-spin chains are characterized by a spin-liquid ground state with no long-range order, due to the relevance of quantum fluctuations. Spin anisotropy, however, freezes quantum fluctuations, and the system is magnetized in the presence of a sufficiently large easy-axis anisotropy. We numerically investigate the case S=1, by means of the density-matrix renormalization group, and find that the freezing of the spin liquid into a Néel spin solid, with increasing easy-axis anisotropy, is a continuous quantum phase transition. Numerical evidence indicates that the transition is not in the two-dimensional Ising universality class.

arXiv:cond-mat/0307266Jul 11, 20031 citation

PHASE TRANSITIONS IN QUANTUM SPIN CHAINS

Jenő Sólyom

WORLD SCIENTIFIC eBooksApr 1, 19920 citations

Quantum Phase Transitions in Spin-Lattice Systems

MANFRED L. RISTIG, Khaled Abu Qasem, DAMIAN J. J. FARNELL

Jan 1, 20010 citations

Neutron Scattering Study of Quantum Phase Transitions in Integer Spin Chains

A. Zheludev

Quite a few low‐dimensional magnets are quantum‐disordered “spin liquids” with a characteristic gap in the magnetic excitation spectrum. Among these are antiferromagnetic chains of integer quantum spins. Their generic feature are long‐lived massive (gapped) excitations (magnons) that are subject to Zeeman splitting in external magnetic fields. The gap in one of the magnon branches decreases with field, driving a soft‐mode quantum phase transition. The system then enters a qualitatively new high‐field phase. The actual properties at high fields, particularly the spin dynamics, critically depend on the system under consideration. Recent neutron scattering studies of organometallic polymer crystals NDMAP (Haldane spin chains with anisotropy) and NTENP (dimerized S = 1 chains) revealed rich and unique physics.Quite a few low‐dimensional magnets are quantum‐disordered “spin liquids” with a characteristic gap in the magnetic excitation spectrum. Among these are antiferromagnetic chains of integer quantum spins. Their generic feature are long‐lived massive (gapped) excitations (magnons) that are subject to Zeeman splitting in external magnetic fields. The gap in one of the magnon branches decreases with field, driving a soft‐mode quantum phase transition. The system then enters a qualitatively new high‐field phase. The actual properties at high fields, particularly the spin dynamics, critically depend on the system under consideration. Recent neutron scattering studies of organometallic polymer crystals NDMAP (Haldane spin chains with anisotropy) and NTENP (dimerized S = 1 chains) revealed rich and unique physics.

arXiv:cond-mat/0507534AIP conference proceedingsJan 1, 20060 citations

Entanglement and quantum phase transitions in quantum mixed spin chains

Shangbin Li, Zhaoxin Xu, Jianhui Dai +1 more

The ground entanglement and thermal entanglement in quantum mixed spin chains consisting of two integer spins 1 and two half-integer spins $\frac{1}{2}$ arrayed as $\frac{1}{2}\text{\ensuremath{-}}\frac{1}{2}\text{\ensuremath{-}}1\text{\ensuremath{-}}1$ in a unit cell with antiferromagnetic nearest-neighbor couplings ${J}_{1}$ $({J}_{2})$ between the spins of equal (different) magnitudes are investigated by employing the logarithmic negativity as entanglement measure. The ground entanglement transition found here is closely related to the valence-bond-solid phase transition, and the thermal entanglement near the critical point is calculated and it is shown that two distinct behaviors exist in the nearest-neighbor same kind of spins and different kind of spins, respectively.The ground entanglement and thermal entanglement in quantum mixed spin chains consisting of two integer spins 1 and two half-integer spins $\frac{1}{2}$ arrayed as $\frac{1}{2}\text{\ensuremath{-}}\frac{1}{2}\text{\ensuremath{-}}1\text{\ensuremath{-}}1$ in a unit cell with antiferromagnetic nearest-neighbor couplings ${J}_{1}$ $({J}_{2})$ between the spins of equal (different) magnitudes are investigated by employing the logarithmic negativity as entanglement measure. The ground entanglement transition found here is closely related to the valence-bond-solid phase transition, and the thermal entanglement near the critical point is calculated and it is shown that two distinct behaviors exist in the nearest-neighbor same kind of spins and different kind of spins, respectively.

arXiv:quant-ph/0508115Physical Review BMay 10, 200616 citations

The ground entanglement and thermal entanglement in quantum mixed spin chains consisting of two integer spins 1 and two half-integer spins

\frac{1}{2}

arrayed as $\frac{1}{2}\text{\ensuremath{-}}\frac{1}{2}\text{\ensuremath{-}}1\text{\ensuremath{-}}1$ in a unit cell with antiferromagnetic nearest-neighbor couplings

{J}_{1}

({J}_{2})

between the spins of equal (different) magnitudes are investigated by employing the logarithmic negativity as entanglement measure. The ground entanglement transition found here is closely related to the valence-bond-solid phase transition, and the thermal entanglement near the critical point is calculated and it is shown that two distinct behaviors exist in the nearest-neighbor same kind of spins and different kind of spins, respectively.