Quantum Phase Transition in a Heisenberg Antiferromagnet on a Square Lattice with Strong Plaquette Interactions

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We present numerical results for an $S=1/2$ Heisenberg antiferromagnet on a inhomogeneous square lattice with tunable interaction between spins belonging to different plaquettes. Employing Quantum Monte Carlo, we significantly improve on previous results for the the critical point separating singlet-disordered and Néel-ordered phases, and obtain an estimate for the critical exponent $ν$ consistent with the three-dimensional classical Heisenberg universality class. Additionally, we show that a fairly accurate result for the critical point can be obtained from a Contractor Renormalization (CORE) expansion by applying a surprisingly simple analysis to the effective Hamiltonian.
4+ pages, 3 figures. Published version

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Strongly Correlated Electrons, Statistical Mechanics

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http://salesiana.dossiersoluciones.com/handle/123456789/170705

Consulte el texto completo en el siguiente enlace:

https://arxiv.org/abs/0807.4389
 http://arxiv.org/abs/0807.4389
 Phys. Rev. B 78, 132402 (2008)
 doi:10.1103/PhysRevB.78.132402

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arXiv