arXiv subjects

Anders Vestergren

Publications and source records attributed to Anders Vestergren.

4 recordsLinked to original sources

arXiv2005

Topological order and the deconfinement transition in the (2+1) dimensional compact Abelian Higgs model

We study an Abelian compact gauge theory minimally coupled to bosonic matter with charge q, which may undergo a confinement--deconfinement transition in (2+1)D. The transition is analyzed using a nonlocal order parameter $\tilde W$, which is related to large Wilson loops for fractional charges. We map the model to a dual representation with no gauge field but only a global q-state clock symmetry and show that $\tilde W$ correspond to the domain wall energy of that model. $\tilde W$ is also directly connected to the concept of topological order. We exploit these facts in Monte Carlo simulations to study the detailed nature of the deconfinement transition.

cond-mat.str-el↗

arXiv2005

Topological Order in the (2+1)D Compact Lattice Superconductor

We study topological aspects of a compact lattice superconductor, and show that the characteristic energy splitting, $Δ$, between almost degenerate ground states, is simply related to a novel order parameter $\tilde W$, which is closely related to large Wilson loops. Using Monte Carlo methods, we study the scaling properties of $\tilde W$ close to the deconfining phase transition, and conclude that $Δ\sim e^{-L/ξ}$, where $L$ is the size of the system, thus giving quantitative support to the vortex tunneling scenario proposed by Wen.

cond-mat.supr-con↗

arXiv2003

Unscreened universality class for superconductors with columnar disorder

The phase transition in a model for vortex lines in high temperature superconductors with columnar defects, i.e., linearly correlated quenched random disorder, is studied with finite size scaling and Monte Carlo simulations. Previous studies of critical properties have mainly focused on the limit of strongly screened vortex line interactions. Here the opposite limit of weak screening is considered. The simulation results provide evidence for a new universality class, with new critical exponents that differ from the case of strong screening of the vortex interaction. In particular, scaling is anisotropic and characterized by a nontrivial value of the anisotropy exponent $ζ=ν_\parallel/ν_\perp$. The exponents we find, $ζ= 1.25 \pm 0.1, ν_\perp=1.0 \pm 0.1, z = 1.95 \pm 0.1$, are similar to certain experimental results on YBCO.

cond-mat.supr-con↗

arXiv2002

Vortex glass transition in a random pinning model

We study the vortex glass transition in disordered high temperature superconductors using Monte Carlo simulations. We use a random pinning model with strong point-correlated quenched disorder, a net applied magnetic field, longrange vortex interactions, and periodic boundary conditions. From a finite size scaling study of the helicity modulus, the RMS current, and the resistivity, we obtain critical exponents at the phase transition. The new exponents differ substantially from those of the gauge glass model, but are consistent with those of the pure three-dimensional XY model.

cond-mat.supr-con↗