Inhomogeneity of the intrinsic magnetic field in superconducting YBa2Cu3OX compounds as revealed by rare-earth EPR-probe

X-band electron paramagnetic resonance on doped Er3+ and Yb3+ ions in Y0.99(Yb,Er)0.01Ba2Cu3OX compounds with different oxygen contents in the wide temperature range (4-120)K have been made. In the superconducting species, the strong dependencies of the linewidth and resonance line position from the sweep direction of the applied magnetic field are revealed at the temperatures significantly below TC. The possible origins of the observed hysteresis are analyzed. Applicability of the presented EPR approach to extract information about the dynamics of the flux-line lattice and critical state parameters (critical current density, magnetic penetration depth, and characteristic spatial scale of the inhomogeneity) is discussedComment: 17 pages, 5 Figures. Renewed versio

Optical microscopy in the nano-world

Scanning near-field optical microscopy (SNOM) is an optical microscopy whose resolution is not bound to the diffraction limit. It provides chemical information based upon spectral, polarization and/or fluorescence contrast images. Details as small as 20 nm can be recognized. Photophysical and photochemical effects can be studied with SNOM on a similar scale. This article reviews a good deal of the experimental and theoretical work on SNOM in Switzerland

Nanosled experiments - determination of dissipation and cohesive energies of C-60 with UHV-SFM

In this study we investigated the tribological properties of C60 thin films which were deposited onto NaCl(001). The used scanning force microscope (SFM) allows simultaneous measurements of normal and lateral forces under ultrahigh vacuum (UHV) conditions. The friction coefficient at the interface between the probing tip (oxidized Si) and the C60-islands is found to be 0.15. By increasing the normal force from 2 to 10 nN, the lateral force on impact with the step edge is sufficient to move the C60 island as an entity in a controlled way and without destroying them. From the analysis of the lateral force signals during the shear event, dissipation and cohesive energies of C60 can be derived. The presented results have impact for the field of nanotechnology, e.g. as a nanosled-type transport system

Cleavage faces of alkaline-earth fluorides studied by atomic force microscopy

An atomic force microscopy (AFM) study of the cleavage faces of CaF2, SrF2 and BaF2 is presented. On the CaF2(111) surface the elementary cleavage structure with cleavage tips has been imaged. The step heights have been determined to be multiples of 0.31 nm, the projection length of the Burgers vector of the primary glide system. Atomic resolution has been achieved in step-free regions of cleavage faces. The hexagonal surface lattice with spacings of 0.38 nm corresponds to the unreconstructed bulk lattice. The 111 surfaces of SrF2 and BaF2 are characterized by a low density of parallel cleavage steps; cleavage tips are not observed. On SrF2 surfaces the formation of erosive holes has been documented by AFM