Quantum groundstates of the spin-1/2 XXZ model on a fully-frustrated honeycomb lattice

Stephen Inglis

Published Oct 1, 2010• 4 citations

Abstract

In this thesis we present results from quantum Monte Carlo for the fully-frustrated honeycomb lattice. \nThe XXZ model is of interest in the classical limit, as there is a mapping between the classical fully-frustrated honeycomb Ising model groundstates and the classical hard-core dimer model groundstate. \nThe aim of this work is to explore the effect of quantum fluctuations on the fully-frustrated honeycomb model to see what sort of interesting physics arises. \nOne might expect unusual physics due to the quantum hard-core dimer model, where interesting physics are known to exist. \nThis is because there is a duality mapping between the classical dimer model and the classical fully-frustrated honeycomb Ising model. \nIndeed, by studying the fully-frustrated honeycomb XXZ model we find that in some cases the system orders into crystal-like structures, a case of order-by-disorder. \nThe most interesting case, when the frustrating bonds are chosen randomly, reveals to us a novel state without any discernible order while at the same time avoiding the freezing one would expect of a glass. \nThis state is a featureless system lacking low temperature magnetic susceptibility---a candidate ``quantum spin liquid''. \nFuture work that might more easily measure quantum spin liquid criteria is suggested.

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