arXiv subjects

A. Wurtz

Publications and source records attributed to A. Wurtz.

4 recordsLinked to original sources

arXiv2005

Topological defects in the edge state structure in a bilayer electron system

We experimentally demonstrate, for the first time, formation of point-like topological defects in the edge state structure in the quantum Hall effect regime. By using of a selective population technique, we investigate equilibration processes between the edge states in bilayer electron structures with a high tunnelling rate between layers. Unexpected flattening of the I-V curves in perpendicular magnetic field at a specific filling factor combination and the recovery of the conventional nonlinear I-V characteristics in tilted fields give a strong evidence for the existence of topological defects.

cond-mat.mes-hall↗

arXiv2004

Manifestation of the bulk phase transition in the edge energy spectrum in a two dimensional bilayer electron system

We use a quasi-Corbino sample geometry with independent contacts to different edge states in the quantum Hall effect regime to investigate the edge energy spectrum of a bilayer electron system at total filling factor $ν=2$. By analyzing non-linear $I-V$ curves in normal and tilted magnetic fields we conclude that the edge energy spectrum is in a close connection with the bulk one. At the bulk phase transition spin-singlet - canted antiferromagnetic phase $I-V$ curve becomes to be linear, indicating the disappearance or strong narrowing of the $ν=1$ incompressible strip at the edge of the sample.

cond-mat.mes-hall↗

arXiv2003

D-branes in lens spaces

We realize the CFT with target a lens space SU(2)/Z_l as a simple current construction. This allows us to compute the boundary states and the annuli coefficients, and in particular to study the B-type branes, in purely algebraic terms. Several issues, like the appearance of fractional branes and symmetry breaking boundary conditions, can be addressed more directly in this approach than in a more geometric treatment.

hep-th↗

arXiv2003

Observation of two relaxation mechanisms in transport between spin split edge states at high imbalance

Using a quasi-Corbino geometry to directly study electron transport between spin-split edge states, we find a pronounced hysteresis in the I-V curves, originating from slow relaxation processes. We attribute this long-time relaxation to the formation of a dynamic nuclear polarization near the sample edge. The determined characteristic relaxation times are 25 s and 200 s which points to the presence of two different relaxation mechanisms. The two time constants are ascribed to the formation of a local nuclear polarization due to flip-flop processes and the diffusion of nuclear spins.

cond-mat.mes-hall↗