29,187 research outputs found
Josephson scanning tunneling microscopy
We propose a set of scanning tunneling microscopy experiments in which the
surface of superconductor is scanned by a superconducting tip. Potential
capabilities of such experimental setup are discussed. Most important
anticipated results of such an experiment include the position-resolved
measurement of the superconducting order parameter and the possibility to
determine the nature of the secondary component of the order parameter at the
surface. The theoretical description based on the tunneling Hamiltonian
formalism is presented.Comment: 6 pages, 7 figures, submitted to Phys. Rev.
Bulk Cr tips for scanning tunneling microscopy and spin-polarized scanning tunneling microscopy
A simple, reliable method for preparation of bulk Cr tips for Scanning
Tunneling Microscopy (STM) is proposed and its potentialities in performing
high-quality and high-resolution STM and Spin Polarized-STM (SP-STM) are
investigated. Cr tips show atomic resolution on ordered surfaces. Contrary to
what happens with conventional W tips, rest atoms of the Si(111)-7x7
reconstruction can be routinely observed, probably due to a different
electronic structure of the tip apex. SP-STM measurements of the Cr(001)
surface showing magnetic contrast are reported. Our results reveal that the
peculiar properties of these tips can be suited in a number of STM experimental
situations
Theory of Scanning Tunneling Microscopy
This lecture has been given at the 45th Spring School: Computing Solids:
Models, Ab-initio Methods and Supercomputing organized at the Forschungszentrum
J\"ulich. The goal of this manuscript is to review the basics behind the theory
accompanying Scanning Tunneling Microscopy.Comment: 38 pages, 45th IFF Spring School: Computing Solids: Models, Ab-initio
Methods and Supercomputing organized at the research center of Juelic
Imaging Pauli repulsion in scanning tunneling microscopy
A scanning tunneling microscope (STM) has been equipped with a nanoscale
force sensor and signal transducer composed of a single D2 molecule that is
confined in the STM junction. The uncalibrated sensor is used to obtain
ultra-high geometric image resolution of a complex organic molecule adsorbed on
a noble metal surface. By means of conductance-distance spectroscopy and
corresponding density functional calculations the mechanism of the
sensor/transducer is identified. It probes the short-range Pauli repulsion and
converts this signal into variations of the junction conductance.Comment: 4 pages, 4 figures, accepted to Phys. Rev. Let
"Oxide-free" tip for scanning tunneling microscopy
We report a new tip for scanning tunneling microscopy and a tip repair procedure that allows one to reproducibly obtain atomic images of highly oriented pyrolytic graphite with previously inoperable tips. The tips are shown to be relatively oxide-free and highly resistant to oxidation. The tips are fabricated with graphite by two distinct methods
Scanning Tunneling Microscopy in the superconductor LaSb2
We present very low temperature (0.15 K) scanning tunneling microscopy and
spectroscopy experiments in the layered superconductor LaSb. We obtain
topographic microscopy images with surfaces showing hexagonal and square atomic
size patterns, and observe in the tunneling conductance a superconducting gap.
We find well defined quasiparticle peaks located at a bias voltage comparable
to the weak coupling s-wave BCS expected gap value (0.17 meV). The amount of
states at the Fermi level is however large and the curves are significantly
broadened. We find T of 1.2 K by following the tunneling conductance with
temperature.Comment: 5 pages, 4 figure
Electrochemical Scanning Tunneling Microscopy
The electrochemical scanning tunneling microscope was the first tool for the investigation of solid–liquid interfaces that allowed in situ real space imaging of electrode surfaces at the atomic level. Therefore it quickly became an important addition to the repertoire of methods
for the determination of the local surface structure as well as the dynamics of reactions and processes taking place at surfaces in an electrolytic environment. In this short overview we present several examples to illustrate the powerful capabilities of the EC-STM, including the observation
of clean metal surfaces as well as the adsorption of thin metal layers, specifically adsorbed anions and non-specifically adsorbed organic cations. In several cases the electrode potential has a significant influence on structure and reactivity of the surface that can be explained by the observations
made with the EC-STM
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