1,279 research outputs found
Majorana lattices from the quantized Hall limit of a proximitized spin-orbit coupled electron gas
Motivated by recent experiments demonstrating intricate quantum Hall physics
on the surface of elemental bismuth, we consider proximity coupling an -wave
superconductor to a two-dimensional electron gas with strong Rashba spin-orbit
interactions in the presence of a strong perpendicular magnetic field. We focus
on the high-field limit so that the superconductivity can be treated as a
perturbation to the low-lying Landau levels. In the clean case, wherein the
superconducting order parameter takes the form of an Abrikosov vortex lattice,
we show that a lattice of hybridized Majorana modes emerges near the plateau
transition of the lowest Landau level. However, unless
magnetic-symmetry-violating perturbations are present, the system always has an
even number of chiral Majorana edge modes and thus is strictly speaking Abelian
in nature, in agreement with previous work on related setups. Interestingly,
however, a weak topological superconducting phase can very naturally be
stabilized near the plateau transition for the square vortex lattice. The
relevance of our findings to potential near-term experiments on proximitized
materials such as bismuth will be discussed.Comment: 13 pages, 9 figure
Novel Phenomena in Dilute Electron Systems in Two Dimensions
We review recent experiments that provide evidence for a transition to a
conducting phase in two dimensions at very low electron densities. The nature
of this phase is not understood, and is currently the focus of intense
theoretical and experimental attention.Comment: To appear as a Perspective in the Proceedings of the National Academy
of Sciences. Reference to Chakravarty, Kivelson, Nayak, and Voelker's paper
added (Phil. Mag., in press
Failure of Scattering Interference in the Pseudogap State of Cuprate Superconductors
We calculate scattering interference patterns for various electronic states
proposed for the pseudogap regime of the cuprate superconductors. The
scattering interference models all produce patterns whose wavelength changes as
a function of energy, in contradiction to the energy-independent wavelength
seen by scanning tunneling microscopy (STM) experiments in the pseudogap state.
This suggests that the patterns seen in STM local density of states
measurements are not due to scattering interference, but are rather the result
of some form of ordering.Comment: To be submitted to Phys. Rev.
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