Magnetic properties and thermal entanglement on a triangulated Kagomé lattice

Abstract

The magnetic and entanglement thermal (equilibrium) properties in spin-1/2 Ising–Heisenberg model on a triangulated Kagomé lattice are analyzed by means of variational mean-field-like treatment based on the Gibbs–Bogoliubov inequality. Because of the separable character of Ising-type exchange interactions between the Heisenberg trimers, the calculation of quantum entanglement in a self-consistent field can be performed for each of the trimers individually. The concurrence in terms of the three-qubit isotropic Heisenberg model in an effective Ising field is non-zero even in the absence of a magnetic field. The magnetic and entanglement properties exhibit common plateau and peak features observable via the (antiferromagnetic) coupling constant and external magnetic field. The critical temperature for the phase transition and threshold temperature for concurrence coincide in the case of antiferromagnetic coupling between qubits. The existence of entangled and disentangled phases in saturated and frustrated phases is established.