[en] It was found that atomically flat Co(110) films could be grown on Cu(110) using O as a surfactant. To obtain detailed knowledge on the effect of O on the growth, as well as on the magnetic properties of Co overlayer, we carried out an investigation on this system using Auger electron spectroscopy, low-energy electron diffraction, surface magneto-optic Kerr effect (SMOKE), and scanning tunneling microscopy. With O as a surfactant, the initial growth of Co (<1 ML) results in a flat monolayer structure. When the Co is thicker than 1 ML, three-dimensional clusters begin to form. These clusters become ordered islands at 3 ML Co and coalesce at ∼5 ML Co. Above 5 ML Co, layer-by-layer growth resumes. No significant Cu segregation is observed. SMOKE studies at room temperature show that the Co film is magnetic above ∼5 ML Co, with the magnetization easy axis along the [001] direction. On the other hand, without using oxygen as a surfactant, Co grows three-dimensionally on Cu(110). The Co overlayer has its easy magnetization axis along the [001] direction, but the onset of the magnetization was observed at 11 ML Co at room temperature

[en] Scanning polarization force microscopy was used to study changes in surface potential (tribocharging) caused by the contact between a tungsten carbide tip and the amorphous carbon coating of a hard disk, both when bare and when covered with Zdol-TX lubricant. The surface potential change produced by tip contact decays with time at a rate that is strongly dependent on lubricant coverage and on the presence of oxygen and water vapor in the environment. Two different charging mechanisms are proposed. One involves chemical modification of the surface by removal of oxygen bound to the surface. This gives rise to a potential change that decays with time. Another mechanism involves trapping of charge in states within the energy gap of the insulating carbon film. The potential change due to this trapped charge does not decay over periods much greater than 1 h

[en] Exposure to beams of low-energy electrons (2-30 keV) in a scanning electron microscope locally induces formation of NV-centers without thermal annealing in diamonds that have been implanted with nitrogen ions. We find that non-thermal, electron-beam-induced NV-formation is about four times less efficient than thermal annealing. But NV-center formation in a consecutive thermal annealing step (800 °C) following exposure to low-energy electrons increases by a factor of up to 1.8 compared to thermal annealing alone. These observations point to reconstruction of nitrogen-vacancy complexes induced by electronic excitations from low-energy electrons as an NV-center formation mechanism and identify local electronic excitations as a means for spatially controlled room-temperature NV-center formation. (paper)

[en] Scanning electron microscopy (SEM) is ubiquitous for imaging but is not generally regarded as a tool for thermal measurements. Here, the temperature dependence of secondary electron (SE) emission from a sample's surface is investigated. Spatially uniform SEM images and the net charge flowing through a sample were recorded at different temperatures to quantify the temperature dependence of SE emission and electron absorption. The measurements also demonstrated charge conservation during thermal cycling by placing the sample inside a Faraday cup to capture the emitted SEs and back-scattered electrons from the sample. The temperature dependence of SE emission was measured for four semiconducting materials (Si, GaP, InP, and GaAs) with response coefficients found to be of magnitudes ~100-1000 ppm/K. The detection limits for temperature changes were no more than ±8 °C for 60 s acquisition time.

[en] The electrical current through the point-contact junction of an AFM tip is used to image the surfaces of bulk graphite (HOPG) and the surface of a graphitized carbon monolayer on Pt(111) under ultra-high-vacuum (UHV) conditions. Lattice-resolved images are obtained simultaneously in topography, lateral friction, and contact current channels. Lattice resolution in current maps persisted up to 0.9 mA and pressures of up to 5 GPa. In both bulk graphite and the case of graphitized carbon monolayer on Pt(111), the current images show only one maximum per unit cell. In addition, the contact current images of the graphite monolayer reveal local conductivity variations. We observed local conductivity variations in the form of moire superstructures resulting from high order commensurability with the Pt lattice. (c) 1999 The American Physical Society

[en] We have fabricated plasmonic bowtie antennae on the apex of silicon atomic-force microscope cantilever tips that enhance the local silicon Raman scattering intensity by ∼4 x 10⁴ when excited near the antenna resonance. The antennae were fabricated using a novel method, induced-deposition mask lithography (IDML), capable of creating high-purity metallic nanostructures on non-planar, non-conducting substrates with high repeatability. IDML involves electron-beam-induced deposition of a W or SiO_x hard mask on the material to be pattered, here a 20 nm Au film, followed by Ar ion etching to remove the mask and the unmasked gold, leaving a chemically pure Au bowtie antenna. Antenna function and reproducibility was confirmed by comparing Raman spectra for excitation polarized parallel and perpendicular to the antenna axis, as well as by dark-field spectroscopic characterization of resonant modes. The field enhancement of these plasmonic AFM antennae tips was comparable with antennae produced by electron-beam lithography on flat substrates.

[en] We exposed nitrogen-implanted diamonds to beams of swift heavy ions (∼1 GeV, ∼4 MeV/u) and find that these irradiations lead directly to the formation of nitrogen vacancy (NV) centers, without thermal annealing. We compare the photoluminescence intensities of swift heavy ion activated NV⁻ centers to those formed by irradiation with low-energy electrons and by thermal annealing. NV⁻ yields from irradiations with swift heavy ions are 0.1 of yields from low energy electrons and 0.02 of yields from thermal annealing. We discuss possible mechanisms of NV center formation by swift heavy ions such as electronic excitations and thermal spikes. While forming NV centers with low efficiency, swift heavy ions could enable the formation of three dimensional NV⁻ assemblies over relatively large distances of tens of micrometers. Further, our results show that NV center formation is a local probe of (partial) lattice damage relaxation induced by electronic excitations from swift heavy ions in diamond