24,271 research outputs found
Direct measurement of penetration length in ultra-thin and/or mesoscopic superconducting structures
We describe a method for direct measurement of the magnetic penetration
length in thin (10 - 100 nm) superconducting structures having overall
dimensions in the range 1 to 100 micrometers. The method is applicable for
broadband magnetic fields from dc to MHz frequencies.Comment: Accepted by Journal of Applied P:hysics (Jun 2006).5 pages, 5 figure
Spin Hall effects for cold atoms in a light induced gauge potential
We propose an experimental scheme to observe spin Hall effects with cold
atoms in a light induced gauge potential. Under an appropriate configuration,
the cold atoms moving in a spatially varying laser field experience an
effective spin-dependent gauge potential. Through numerical simulation, we
demonstrate that such a gauge field leads to observable spin Hall currents
under realistic conditions. We also discuss the quantum spin Hall state in an
optical lattice.Comment: 4 pages; The published versio
Edge state effects in junctions with graphene electrodes
We consider plane junctions with graphene electrodes, which are formed by a
single-level system ("molecule") placed between the edges of two single-layer
graphene half planes. We calculate the edge Green functions of the electrodes
and the corresponding lead self-energies for the molecular levels in the cases
of semi-infinite single-layer electrodes with armchair and zigzag edges. We
show two main effects: first, a peculiar energy-dependent level broadening,
reflecting at low energies the linear energy dependence of the bulk density of
states in graphene, and, second, the shift and splitting of the molecular level
energy, especially pronounced in the case of the zigzag edges due to the
influence of the edge states. These effects give rise to peculiar conductance
features at finite bias and gate voltages.Comment: 8 pages, 8 figures, submitted to PR
Tracing potential energy surfaces of electronic excitations via their transition origins: application to Oxirane
We show that the transition origins of electronic excitations identified by
quantified natural transition orbital (QNTO) analysis can be employed to
connect potential energy surfaces (PESs) according to their character across a
widerange of molecular geometries. This is achieved by locating the switching
of transition origins of adiabatic potential surfaces as the geometry changes.
The transition vectors for analysing transition origins are provided by linear
response time-dependent density functional theory (TDDFT) calculations under
the Tamm-Dancoff approximation. We study the photochemical CO ring opening of
oxirane as an example and show that the results corroborate the traditional
Gomer-Noyes mechanism derived experimentally. The knowledge of specific states
for the reaction also agrees well with that given by previous theoretical work
using TDDFT surface-hopping dynamics that was validated by high-quality quantum
Monte Carlo calculations. We also show that QNTO can be useful for considerably
larger and more complex systems: by projecting the excitations to those of a
reference oxirane molecule, the approach is able to identify and analyse
specific excitations of a trans-2,3-diphenyloxirane molecule.Comment: 14 pages, 12 figure
- …