By using a low temperature scanning tunneling microscope we have probed the superconducting energy gap of epitaxially grown Pb films as function layer thickness in an ultrathin regime (5-18 ML). The layer-dependent and transition (Tc) show persistent quantum oscillations down to lowest without any sign suppression. Moreover, by comparison with quantum-well states measured above Tc theoretical calculations, found that oscillation correlates directly density at E(F) . is manifested phase...

We have grown well-ordered graphene adlayers on the lattice-matched Co(0001) surface. Low-temperature scanning tunneling microscopy measurements demonstrate an on-top registry of carbon atoms with respect to The conductance spectrum shows that electronic structure is substantially altered from isolated graphene, implying a strong coupling between and cobalt states. Calculations using density functional theory confirm structures lowest energy provide clear evidence for pi-states Co d-states...

The focusing performance of a multilayer Laue lens (MLL) with 43.4 μm aperture, 4 nm finest zone width and 4.2 mm focal length at 12 keV was characterized X-rays using ptychography method. reconstructed probe shows full-width-at-half-maximum (FWHM) peak size 11.2 nm. obtained X-ray wavefront excellent agreement the dynamical calculations, exhibiting aberrations less than 0.3 wave period, which ensures MLL capable producing diffraction-limited focus while offering sufficient working distance....

The reduced surface of a natural Hematite single crystal α-Fe2O3(0001) sample has multiple domains with different terminations, Fe2O3(0001), FeO(111), and Fe3O4(111). adsorption water on this was investigated via Scanning Tunneling Microscopy (STM) first-principle theoretical simulations. Water species are observed only the Fe-terminated Fe3O4(111) at temperatures up to 235 K. Between 245 K we change in from intact molecules hydroxyl groups bound atop terminating FeIII cations. This...

We present a scanning tunneling microscopy (STM)/scanning spectroscopy (STS) study of model catalyst system consisting supported gold nanoparticles on reduced Fe3O4(111) surface in ultrahigh vacuum. Gold forms two electrically distinct an iron oxide upon annealing multilayer Au/Fe3O4(111) at 500 °C for 15 min. I (V) curves taken via STS measurements show that large (∼8 nm) exhibit metallic electronic structure and, thus, are likely neutral. Single adatoms appear to be strongly bonded the...

We describe scanning tunneling microscopy and X-ray photoelectron spectroscopy studies of graphene films produced by sonication-assisted dispersion. Defects in these samples are not randomly distributed, the exhibit a "patchwork" structure where unperturbed areas adjacent to heavily functionalized ones. Adjacent layers likely poor mechanical contact due adventitious species trapped between carbon sheets sample.

Low-temperature scanning tunneling microscopy measurements and first-principles calculations are employed to characterize edge structures observed for graphene nanoislands grown on the Co(0001) surface. Images of these nanostructures reveal straight well-ordered edges with zigzag orientation, which characterized by a distinct peak at low bias in spectra. Density functional theory based used discriminate between candidate structures. Several zigzag-oriented have lower formation energy than...

Synchrotron based x-ray microscopy established itself as a prominent tool for noninvasive investigations in many areas of science and technology. Many facilities around the world routinely achieve sub-micrometer resolution with few instruments capable imaging spatial better than 100 nm. With an ongoing effort to push 2D/3D down 10 nm hard regime both fabrication nano-focusing optics stability microscope become extremely challenging. In this work we present our approach overcome technical...

Kekulé distortion in graphene is a subject of extensive theoretical studies due to its non-trivial material properties. Yet, experimental observation formation mechanism and electronic structures still elusive. Here, we used scanning tunneling microscopy visualize two different phases the along with evidence that local strain responsible for such distortions. In addition, directly measured revealing one opens an energy gap whereas other maintains linear density profile. These are consistent...

We have designed and constructed a dedicated instrument to perform ptychography measurements characterization of multilayer Laue lenses nanofocusing optics. The design the scanning microscope provides stability components minimal thermal drifts, requirements for nanometer scale spatial resolution measurements. performed thorough laboratory in terms drifts with subsequent at synchrotron. successfully acquired reconstructed data yielding 11 nm line focus.

We demonstrate a novel scheme for manipulating metallic nanostructures involving macroscopic number of atoms, yet with precise control in their local structures. The entails two-step process: (a) triggering step using scanning tunneling microscope, followed by (b) self-driven and self-limiting mass-transfer process. By this scheme, we construct Pb nanomesas on Si(111) substrates whose thickness can be controlled atomic-layer precision. kinetic barrier the mass transfer underlying mechanism...

We report on the design of a compact low temperature scanning tunneling microscope (STM) having in-situ sample preparation capability. The chamber was designed to be allowing quick transfer samples STM stage, which is ideal for preparing sensitive such as ultra-thin metal films semiconductor substrates. Conventional spring suspensions head often cause mechanical issues. To address this problem, we developed simple vibration damper consisting welded bellows and rubber pads. In addition, novel...

Controlling the self-assembly of surface-adsorbed molecules into nanostructures requires understanding physical mechanisms that act across multiple length and time scales. By combining scanning tunneling microscopy with hierarchical ab initio statistical mechanical modeling 1,4-substituted benzenediamine (BDA) adsorbed on a gold (111) surface, we demonstrate apparently simple are selected by subtle competition thermodynamics dynamics. Of collection possible BDA mechanically stabilized...

We show that each surface atom of heavily boron-doped, (111)-oriented silicon with a √3 × reconstruction has electrically switchable two charge states due to the strong electron-lattice coupling at this surface. The structural and electronic properties as well their energetics are uncovered by employing scanning tunneling microscopy measurements density functional theory calculations, which reveals one is two-electron bound state or bipolaron. also execute single-atom bit operations on...

The demand for better understanding of the mechanism soot formation is driven by negative environmental and health impact brought about burning fossil fuels. While particles accumulate most their mass from surface reactions, growth has so far been characterized primarily measurements kinetics. Here we provide atomic-scale scanning tunneling microscope images carbon chemistry similar to that importance in formation. At a temperature 625 K, exposure highly ordered pyrolytic graphite 1 Langmuir...

Charge doping to Mott insulators is critical realize high-temperature superconductivity, quantum spin liquid state, and Majorana fermion, which would contribute computation. also have a great potential for optoelectronic applications; however, they showed insufficient photoresponse in previous reports. To enhance the of insulators, charge promising strategy since it leads effective modification electronic structure near Fermi level. Intercalation, ion insertion into van der Waals gap layered...

Abstract An enormous amount of research activities has been devoted to developing new types non-volatile memory devices as the potential replacements current flash devices. Theoretical device modeling was performed demonstrate that a huge change tunnel resistance in an Edge Metal-Insulator-Metal (EMIM) junction metal crossbar structure can be induced by modulation electric fringe field, associated with polarization reversal underlying ferroelectric layer. It is demonstrated single...

The crystallinity of epitaxial graphene (EG) grown on a Hexagonal-SiC substrate is found to be enhanced greatly by capping the with molybdenum plate (Mo-plate) during vacuum annealing. enhancement EG layer Mo-plate confirmed significant change measured Raman spectra, compared spectra for no capping. considered induce heat accumulation SiC surface thermal radiation mirroring and raise Si partial pressure near confining sublimated atoms between Mo-plate, which would essential contributors enhancement.

Initial adsorption of CO molecules on Si(001) is investigated by using room-temperature (RT) scanning tunneling microscopy (STM) and density functional theory calculations. Theoretical calculations show that only one configuration terminal-bound (T-CO) stable the bridge-bound unstable. All abundantly observed STM features due to can be identified as differently configured T-COs. The initial sticking probability at RT estimated small ∼1 × 10–4 monolayer/Langmuir, which significantly increased...

Dielectric screening is essential in determining semiconductor properties. Its assessment on the surface, however, beyond capability of conventional techniques due to their lack surface sensitivity. Here we present surface-sensitive measurement dielectric by using scanning tunneling microscopy and spectroscopy. Both single-atom single-electron manipulations B $\ensuremath{\delta}$-doped Si(111) unravel that this much excess what classical image-charge model predicts, which ascribe strained...

By using scanning tunneling spectroscopy to probe a silver thin film that contains both periodic and quasiperiodic modulation, by Fourier analysis, we unravel the influences of individual components scattering potential (periodic versus quasiperiodic) on electronic structure one-dimensional quasiperiodically modulated Ag film. Along periodically direction, Bragg reflection-induced energy gap is observed in k space. On other hand, exotic E vs spectrum with many minigaps was along direction.

Abstract The effective work‐function of metal electrode is one the major factors to determine threshold voltage metal/oxide/semiconductor junction. In this work, it demonstrated experimentally that Aluminum (Al) in Al/SiO 2 /n‐Si junction increases significantly by ≈1.04 eV with graphene interlayer inserted at interface. device‐physical analysis solving Poisson equation analytically provided when flat‐band applied junction, supporting large tuning Al may originate from electric dipole layer...

A charged vacancy on the Si surface, which generates deep levels within band gap to accommodate multiple charge states, becomes increasingly important with device scaling. Yet its characteristics have not been addressed as comprehensively bulk in Si. Here we generate adatom vacancies a heavily B doped Si(111) surface and measure their structural electronic properties by using scanning tunneling microscopy. We find that they are Jahn-Teller distorted ground state but undergo...