The two dimensional Antiferromagnetic Heisenberg model with next nearest neighbour Ising exchange

Abstract

We have considered the $S=1/2$ antiferromagnetic Heisenberg model in two dimensions, with an additional Ising \nnn interaction. Antiferromagnetic \nnn interactions will lead to frustration, and the system responds with flipping the spins down in the $xy$ plane. For large next nearest neighbour coupling the system will order in a striped phase along the z axis, this phase is reached through a first order transition. We have considered two generalizations of this model, one with random \nnn interactions, and one with an enlarged unit cell, where only half of the atoms have \nnn interactions. In both cases the transition is softened to a second order transition separating two ordered states. In the latter case we have estimated the quantum critical exponent $\beta \approx 0.25$. These two cases then represent candidate examples of deconfined quantum criticality.

Extensive revisions. Two new models with contious quantum phase transition

References in corpus (8)

• "Deconfined" quantum critical points
• Quantum Monte Carlo study of S=1/2 weakly-anisotropic antiferromagnets on the square lattice
• First-order phase transition in easy-plane quantum antiferromagnets
• Monte Carlo Study of Phase Transitions in the Bond-Diluted 3D 4-State Potts Model
• Two-Dimensional Quantum XY Model with Ring Exchange and External Field
• Anisotropy-induced ordering in the quantum J1-J2 antiferromagnet
• On the Melting of Bosonic Stripes
• Quantum phases and phase transitions of Mott insulators

Cited by in corpus (1)

• Bosonization duality in 2+1 dimensions and critical current correlation functions in Chern-Simons $U(1)\times U(1)$ Abelian Higgs model