Phase transitions and thermal entanglement of the distorted IsingHeisenberg spin chain: topology of multiplespin exchange interactions in spin ladders
Abstract
We consider a symmetric spin1/2 IsingXXZ double sawtooth spin ladder obtained from distorting a spin chain, with the XXZ interaction between the interstitial Heisenberg dimers (which are connected to the spins based on the legs via an Isingtype interaction), the Ising coupling between nearestneighbor spins of the legs and rungs spins, respectively, and additional cyclic fourspin exchange (ring exchange) in the square plaquette of each block. The presented analysis supplemented by results of the exact solution of the model with infinite periodic boundary implies a rich ground state phase diagram. As well as the quantum phase transitions, the characteristics of some of the thermodynamic parameters such as heat capacity, magnetization and magnetic susceptibility are investigated. We prove here that among the considered thermodynamic and thermal parameters, solely heat capacity is sensitive versus the changes of the cyclic fourspin exchange interaction. By using the heat capacity function, we obtain a singularity relation between the cyclic fourspin exchange interaction and the exchange coupling between pair spins on each rung of the spin ladder. All thermal and thermodynamic quantities under consideration should be investigated by regarding those points which satisfy the singularity relation. The thermal entanglement within the Heisenberg spin dimers is investigated by using the concurrence, which is calculated from a relevant reduced density operator in the thermodynamic limit.
 Publication:

Journal of Physics Condensed Matter
 Pub Date:
 November 2017
 DOI:
 10.1088/1361648X/aa8dd0
 arXiv:
 arXiv:1710.08713
 Bibcode:
 2017JPCM...29S5402A
 Keywords:

 Condensed Matter  Statistical Mechanics;
 Quantum Physics
 EPrint:
 J. Phys.: Condens. Matter 29 (2017) 455402