Kink confinement in the antiferromagnetic XXZ spin(1/2) chain in a weak staggered magnetic field
Abstract
The Heisenberg XXZ spin(1/2) chain is considered in the massive antiferromagnetic regime in the presence of a staggered longitudinal magnetic field. The Hamiltonian of the model is characterised by the anisotropy parameter Δ<1 and by the magneticfield strength h. At zero magnetic field, the model is exactly solvable. In the thermodynamic limit, it has two degenerate vacua and the kinks (which are also called spinons) interpolating between these vacua, as elementary excitations. Application of the staggered magnetic field breaks integrability of the model and induces the longrange attractive potential between two adjacent kinks leading to their confinement into the bound states. The energy spectra of the resulting twokink bound states are perturbatively calculated in the extreme anisotropic (Ising) limit Δ\to∞ to the first order in the inverse anisotropy constant Δ^{1} , and also for any Δ<1 to the first order in the weak magnetic field h.
 Publication:

EPL (Europhysics Letters)
 Pub Date:
 February 2018
 DOI:
 10.1209/02955075/121/37001
 arXiv:
 arXiv:1710.11605
 Bibcode:
 2018EL....12137001R
 Keywords:

 Condensed Matter  Statistical Mechanics;
 Condensed Matter  Strongly Correlated Electrons
 EPrint:
 publishes version, minor changes, misprints corrected