Quantum Spin Chains with Regularly Alternating Bonds and Fields
نویسنده
چکیده
We consider the spin1 2 XY chain in a transverse field with regularly varying exchange interactions and on-site fields. In two limiting cases of the isotropic (XX) and extremely anisotropic (Ising) exchange interaction the thermodynamic quantities are calculated rigorously with the help of continued fractions. We discuss peculiarities of the low-temperature magnetic properties and a possibility of the spin-Peierls instability. PACS numbers: 75.10.-b
منابع مشابه
Quantum Phase Transitions in Alternating Transverse Ising Chains
This chapter is devoted to a discussion of quantum phase transitions in regularly alternating spin1 2 Ising chain in a transverse field. After recalling some generally-known topics of the classical (temperature-driven) phase transition theory and some basic concepts of the quantum phase transition theory I pass to the statistical mechanics calculations for a one-dimensional spin1 2 Ising model ...
متن کاملQuantum phase transitions in alternating transverse Ising chains: Rigorous analytical and exact numerical results
We examine the ground state properties of the s = 1 2 transverse Ising chain with regularly alternating bonds and fields using exact analytical results and exact numerical data for long (up to N = 900) and short (N = 20) chains. For a given period of alternation the system may exhibit a series of quantum phase transitions, where the number of transitions depends on the concrete set of the param...
متن کاملIsing Chain in Regularly Alternating Transverse Field: Spin Correlation Functions
We consider the spin1 2 Ising chain in a regularly alternating transverse field to examine the effects of regular alternation on the quantum phase transition inherent in the quantum Ising chain. The number of quantum phase transition points strongly depends on the specific set of the Hamiltonian parameters but never exceeds 2p where p is the period of alternation. Calculating the spin correlati...
متن کاملExact S Matrices for Integrable Quantum Spin Chains Luca
We begin with a review of the antiferromagnetic spin 1/2 Heisenberg chain. In particular, we show that the model has particle-like excitations with spin 1/2, and we compute the exact bulk S matrix. We then review our recent work which generalizes these results. We first consider an integrable alternating spin 1/2 spin 1 chain. In addition to having excitations with spin 1/2, this model also has...
متن کاملThere is life in the old horse yet or what else we can learn studying spin - 1 2 XY chains
There is life in the old horse yet or what else we can learn studying spin-We review some recent results on statistical mechanics of the one-dimensional spin-1 2 XY systems paying special attention to the dynamic and thermodynamic properties of the models with Dzyaloshinskii-Moriya interaction, correlated disorder , and regularly alternating Hamiltonian parameters.
متن کامل