41 research outputs found
Tuning Yu-Shiba-Rusinov States in a Quantum Dot
We present transport spectroscopy of sub-gap states in a bottom gated InAs
nanowire coupled to a normal lead and a superconducting aluminium lead. The
device shows clearly resolved sub-gap states which we can track as the coupling
parameters of the system are tuned and as the gap is closed by means of a
magnetic field. We systematically extract system parameters by using numerical
renormalization group theory fits as a level of the quantum dot is tuned
through a quantum phase transition electrostatically and magnetically. We also
give an intuitive description of sub-gap excitations.Comment: 9 pages, 10 figure
Fast Characterization of Moving Samples with Nano-Textured Surfaces
We characterize nano-textured surfaces by optical diffraction techniques
using an adapted commercial light microscope with two detectors, a CCD camera
and a spectrometer. The acquisition and analyzing time for the topological
parameters height, width, and sidewall angle is only a few milliseconds of a
grating. We demonstrate that the microscope has a resolution in the nanometer
range, also in an environment with many vibrations, such as a machine floor.
Furthermore, we demonstrate an easy method to find the area of interest with
the integrated CCD camera.Comment: 19 pages, 4 figure
Advances in the theory of III-V Nanowire Growth Dynamics
Nanowire (NW) crystal growth via the vapour_liquid_solid mechanism is a
complex dynamic process involving interactions between many atoms of various
thermodynamic states. With increasing speed over the last few decades many
works have reported on various aspects of the growth mechanisms, both
experimentally and theoretically. We will here propose a general continuum
formalism for growth kinetics based on thermodynamic parameters and transition
state kinetics. We use the formalism together with key elements of recent
research to present a more overall treatment of III_V NW growth, which can
serve as a basis to model and understand the dynamical mechanisms in terms of
the basic control parameters, temperature and pressures/beam fluxes.
Self-catalysed GaAs NW growth on Si substrates by molecular beam epitaxy is
used as a model system.Comment: 63 pages, 25 figures and 4 tables. Some details are explained more
carefully in this version aswell as a new figure is added illustrating
various facets of a WZ crysta