Analysis of a potential solution to the simple cubic three-dimensional Ising model

Following a novel approach to solve sofar unsolved Ising problems like the 3D-problem for the simple cubic isotropic lattice, the authors brought forward a potential solution. This potential solution is analyzed to illustrate various aspects of the approach and is replaced by another

Atomic manipulation on semiconductor surfaces at room temperature by Scanning Tunneling Microscopy

The scanning tunnelling microscope (STM) can be used as a tool for assembling nanostructures at the atomic level. In this article we briefly review several pathways for controlled manipulation of atoms and molecules on semiconductor surfaces at room temperature. As an illustrative example we discuss the controlled manipulation of atomic platinum chains. We were able to carry the constituting dimers of the atomic Pt chains from point to point with atomic precision at room temperature. Besides the ultimate control of the surface structure we also show that the manipulated Pt dimer can be attached to the apex of the STM tip in various stable configurations

Rectification behaviour of molecular layers on Si(111)

Reproducible and strong diode-like behaviour is observed for molecular films of 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) on n-type Si(111)- 7×7 surfaces studied by scanning tunnelling microscopy (STM) and spectroscopy (STS) at 77 K. The mechanism behind the rectification is likely to be related to the electron distribution at the molecule-silicon interface. We suggest that the adsorption of the molecular layer profoundly modifies the electronic structure of the Si(111)- 7×7 surface

Atomic seesaws

The dynamics of two types of atomic seesaws are studied by open feedback loop scanning tunneling microscopy. The first type of atomic seesaw is a regular Ge dimer of the dimer reconstructed Ge(001) surface and the second type of atomic seesaw is a dimer located on the ridges of Au induced nanowires on a Ge(001) surface. On the bare Ge(001) surface the flip-flop motion of the dimers is induced by phasons, which perform a one-dimensional random walk along the substrate dimer rows. The phasons on the Au induced nanowires ridges are pinned and therefore only a limited number of dimers exhibit flip-flop behavior for the Au/Ge(001) system

Selective metallization by seeded growth on patterned gold nanoparticle arrays

We describe the selective metallization by electroless gold deposition on pre-patterned arrays of seed particles. In the first step, highly selective deposition of seeds (gold nanoparticles) on silicon oxide surfaces is achieved using pure water. In the second step, employing an electroless seeded growth process, the isolated nanoparticles are enlarged beyond the percolation threshold to deposit conducting metal structures. We obtain patterned gold films which exhibit macroscopic conductivity values approximately a factor of three lower than that of bulk gold. The surface morphology of the films has been characterized by scanning electron microscopy and spectroscopic ellipsometry. We discuss the different regimes as observed in morphological, electrical, and optical characterization in relation to each other. The free electron contribution to the optical spectra is analyzed in terms of the Drude model. Also, the formation of gold clusters during the growth process in the non-seeded area is described

Size fluctuations of near critical and Gibbs free energy for nucleation of BDA on Cu(001)

We present a low-energy electron microscopy study of nucleation and growth of BDA on Cu(001) at low supersaturation. At sufficiently high coverage, a dilute BDA phase coexists with c(8×8) crystallites. The real-time microscopic information allows a direct visualization of near-critical nuclei, determination of the supersaturation and the line tension of the crystallites, and, thus, derivation of the Gibbs free energy for nucleation. The resulting critical nucleus size nicely agrees with the measured value. Nuclei up to 4-6 times larger still decay with finite probability, urging reconsideration of the classic perception of a critical nucleus

Inelastic electron tunneling spectroscopy on decanethiol at elevated temperatures

Inelastic electron tunneling spectroscopy (IETS) measurements using scanning tunneling microscopy (STM) on a decanethiol self-assembled monolayer on Au(111) are presented. The results presented are obtained in the temperature range 77-300 K, which is a much higher temperature than what is commonly used for STM-IETS measurements. Two peaks at ±34 meV (probably Au-S or S-C stretch mode) and ±156 meV (C-C stretch mode or a CH2 mode) are resolved

Vacancy-mediated diffusion of Co atoms embedded in Cu(001)

The diffusion of Co atoms in the Cu(001) surface has been studied using Scanning Tunneling Microscopy (STM). Like other impurities in the Cu(001) surface, the diffusion of Co is mediated by single surface vacancies. STM images reveal that diffusion of the embedded atoms takes place through multi-atom jumps separated by long time intervals, which is characteristic for this type of diffusion. The jump length and frequency are measured to establish the nature of the interaction between surface vacancies and the embedded Co atoms and to extract the relevant formation and diffusion energies

Formation of nanowires and their interaction with atomic steps during growth of Bi on Ni(111)

Using low-energy electron microscopy (LEEM) and selective area low-energy electron diffraction, we have characterized both the (7×7) wetting layer and the BiNi9 [2 0 −2 5] nanowires that form during the growth of Bi on Ni(111). The 60 ± 20 nm wide nanowires have lengths up to 10 μm and a height of 4–6 atomic layers. After the formation of the wetting layer and nanowires, quantum size effect driven growth ensues, accompanied by the gradual disappearance of the nanowires and resulting meandering of the substrate steps. The displacements of substrate steps, directly imaged with LEEM, can be traced back to dealloying