Ying Tang - Preliminary Oral Exam

When: February 28, 2011 (Mon), 10:00AM to 11:00AM (add to my calendar)
Location: SCI 328

This event is part of the Preliminary Oral Exam.

Title: Properties of Resonating-Valence-Bond Spin Liquids and
Critical Dimer Models

Examining Committee: Anders Sandvik, Richard Averitt, Claudio Chamon, Emanuel Katz

Abstract:
We use Monte Carlo simulations to study properties of Anderson’s resonating-
valence-bond (RVB) spin-liquid state on the square lattice and compare these
results with a similar state – the ground state of the quantum dimer model
at its critical point (the Rokhsar-Kivelson point), which also corresponds
to the statistical mechanics of the classical dimer model (CDM). We measured
the dimer-dimer (4-spin) correlations and found that in both RVB and
CDM states, dimer-dimer correlations decay as a power-law. In RVB, the
dimer-dimer correlations decay more slowly than in CDM. We also measured
the monomer deconfinement and topological winding number sector prob-
abilities in both states and found qualitatively similar but quantitatively
different properties between RVB and CDM. We further framed our RVB
studies to a classical field theory (height model) which is characterized by a
gradient-squared stiffness constant K. We did four independent
measurements of K and found KRVB ≈ 1.6KCDM , which indicates a plausibility of
the height model approach for SU(2) spins (RVB) by a renormalization of the
stiffness constant. We also extended our work to long bond RVB and CDM
and obtained a smooth reduction of K as expected.