Equilibrium and dynamical properties of the ANNNI chain at the multiphase point
Abstract
We study the equilibrium and dynamical properties of the ANNNI (axial next-nearest-neighbor Ising) chain at the multiphase point. An interesting property of the system is the macroscopic degeneracy of the ground state leading to finite zero-temperature entropy. In our equilibrium study we consider the effect of softening the spins. We show that the degeneracy of the ground state is lifted and there is a qualitative change in the low temperature behaviour of the system with a well defined low temperature peak of the specific heat that carries the thermodynamic ``weight'' of the ground state entropy. In our study of the dynamical properties, the stochastic Kawasaki dynamics is considered. The Fokker-Planck operator for the process corresponds to a quantum spin Hamiltonian similar to the Heisenberg ferromagnet but with constraints on allowed states. This leads to a number of differences in its properties which are obtained through exact numerical diagonalization, simulations and by obtaining various analytic bounds.
Cite
@article{arxiv.cond-mat/0004207,
title = {Equilibrium and dynamical properties of the ANNNI chain at the multiphase point},
author = {Abhishek Dhar and B. Sriram Shastry and Chandan Dasgupta},
journal= {arXiv preprint arXiv:cond-mat/0004207},
year = {2009}
}
Comments
9 pages, RevTex, 6 figures (To appear in Phys. Rev. E)