Quantum compass model on the square lattice

Quantum model of interacting “ strings ” on the square lattice

Quantum model of interacting " strings " on the square lattice Abstract The model which is the generalization of the one-dimensional XY-spin chain for the case of the two-dimensional square lattice is considered. The subspace of the " string " states is studied. The solution to the eigenvalue problem is obtained for the single " string " in cases of the " string " with fixed ends and " string "...

Compass model on a ladder and square clusters

We obtained exact heat capacities of the quantum compass model on the square L×L clusters with L = 2, 3, 4, 5 using Kernel Polynomial Method and compare them with heat capacity of a large compass ladder. Intersite correlations found in the ground state for these systems demonstrate that the quantum compass model differs from its classical version. Quantum compass model originating from the orbi...

Doping quantum dimer models on the square lattice

Random-exchange quantum Heisenberg antiferromagnets on a square lattice

Nicolas Laflorencie,1 Stefan Wessel,2 Andreas Läuchli,3 and Heiko Rieger4 1Department of Physics & Astronomy, University of British Columbia, Vancouver, B.C., Canada V6T 1Z1 2Institut für Theoretische Physik III, Universität Stuttgart, 70550 Stuttgart, Germany 3Institut Romand de Recherche Numérique en Physique des Matériaux, EPFL, 1015 Lausanne, Switzerland 4Theoretische Physik, Universität de...

Quantum phase transition in the quantum compass model

In this work, we show that the quantum compass model on a square lattice can be mapped to a fermionic model with local-density interaction. We introduce a mean-field approximation where the most important fluctuations, those perpendicular to the ordering direction, are taken into account exactly. It is found that the quantum phase transition point at Jx=Jz marks a first-order phase transition. ...