arXiv subjects

Julia Wildeboer

Publications and source records attributed to Julia Wildeboer.

21 records · Page 2Linked to original sources

arXiv2012

Correlation functions in SU(2)-invariant RVB spin liquids on nonbipartite lattices

We introduce a Monte Carlo scheme based on sampling of Pfaffians to investigate Anderson's resonating-valence-bond (RVB) spin liquid wave function on the kagome and the triangular lattice. This eliminates a sign problem that prevents utilization of the valence bond basis in Monte Carlo studies for non-bipartite lattices. Studying lattice sizes of up to 600 sites, we calculate singlet-singlet and spin-spin correlations, and demonstrate how the lattice symmetry is restored within each topological sector as the system size is increased. Our findings are consistent with the expectation that the nearest neighbor RVB states describe a topological spin liquid on these non-bipartite lattices.

cond-mat.str-el↗

arXiv2012

Linear independence of nearest-neighbor valence bond states in several two-dimensional lattices

We show for several two-dimensional lattices that the nearest neighbor valence bond states are linearly independent. To do so, we utilize and generalize a method that was recently introduced and applied to the kagome lattice by one of the authors. This method relies on the choice of an appropriate cell for the respective lattice, for which a certain local linear independence property can be demonstrated. Whenever this is achieved, linear independence follows for arbitrarily large lattices that can be covered by such cells, for {\em both} open and periodic boundary conditions. We report that this method is applicable to the kagome, honeycomb, square, squagome, two types of pentagonal, square-octagon, the star lattice, two types of archimedean lattices, three types of "martini" lattices, and to fullerene-type lattices, e.g., the well known "Buckyball". Applications of the linear independence property, such as the derivation of effective quantum dimer models, or the constructions of new solvable spin-1/2 models, are discussed.

cond-mat.str-el↗

arXiv2011

Destruction of valence-bond order in a $S=1/2$ sawtooth chain with a Dzyaloshinskii-Moriya term

A small value of the spin gap in quantum antiferromagnets with strong frustration makes them susceptible to nominally small deviations from the ideal Heisenberg model. One of such perturbations, the anisotropic Dzyaloshinskii-Moriya interaction, is an important perturbation for the $S=1/2$ kagome antiferromagnet, one of the current candidates for a quantum-disordered ground state. We study the influence of the DM term in a related one-dimensional system, the sawtooth chain that has valence-bond order in its ground state. Through a combination of analytical and numerical methods, we show that a relatively weak DM coupling, $0.115J$, is sufficient to destroy the valence-bond order, close the spin gap, and turn the system into a Luttinger liquid with algebraic spin correlations. A similar mechanism may be at work in the kagome antiferromagnet.

cond-mat.str-el↗