J.D. Pedarnig

Noncontact scanning force microscopy based on a modified tuning fork sensor

Distance control using a tuning fork setup for the detection of shear forces is a standard configuration in scanning near-field optical microscopy (SNOM). Based on this concept, a modified sensor was developed, where a standard silicon tip for atomic force microscopy (AFM) is attached to the front end of one prong of a 100 kHz quartz tuning fork oscillator. Comparison of force curves of a standard tapping-mode AFM cantilever, a conventional fiber tip SNOM sensor and the novel AFM tip shear force sensor demonstrate an enhanced stability and sensitivity of the new sensor. Due to the rigid sensor design the force curves of the AFM tip shear force sensor indicate a perfect noncontact behavior under normal conditions in air. Noncontact images show a comparable resolution to conventional force microscopy.

Double sign reversal of the vortex Hall effect in YBa 2 Cu 3 O 7 − δ thin films in the strong pinning limit of low magnetic fields

Measurements of the Hall effect and the resistivity in twinned

Laser-induced breakdown spectroscopy of iron oxide powder

{\mathrm{YBa}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{7\ensuremath{-}\ensuremath{\delta}}

Bi2Sr2Can-1CunO2(n+2)+δ thin films on c-axis oriented and vicinal substrates

thin films in magnetic fields B oriented parallel to the crystallographic c axis and to the twin boundaries reveal a double sign reversal of the Hall coefficient for

Electrical properties, texture, and microstructure of vicinal YBa2Cu3O7−δ thin films

Bl~1

Anomalous Hall effect and vortex pinning in high-Tc superconductors

T. In high transport current densities, or with B tilted off the twin boundaries by

Anisotropic resistivity in off-c-axis grown Bi2Sr2CaCu2O8 films

5\ifmmode^\circ\else\textdegree\fi{},

Giant dielectric permittivity and electromechanical strain in thin film materials produced by pulsed-laser deposition

the second sign reversal vanishes. The power-law scaling of the Hall conductivity to the longitudinal conductivity in the mixed state is strongly modified in the regime of the second sign reversal. Our observations are interpreted as strong, disorder-type dependent vortex pinning and confirm that the Hall conductivity in high-temperature superconductors is not independent of pinning.

PHOTOINDUCED ENHANCEMENT OF THE C-AXIS CONDUCTIVITY IN OXYGEN-DEFICIENT YBA2CU3OX THIN FILMS

Iron oxide Fe2O3 nano-particle powder is investigated by laser-induced breakdown spectroscopy (LIBS). Laser ablation of loose Fe2O3 powder (density 0.43 g cm−3) leads to the ejection of particles and generates a plasma channel along the laser beam path. LIBS spectra are obtained by spatially integrated and time-gated measurement in flushed N2 gas background. A simple powder delivery system allows for investigation of the nano-particle powder directly without any pre-treatment and fixation of the loose material. The Saha–Boltzmann analysis of spectra yields plasma temperature T = (10250 ± 200) K and electron density Ne = (11 ± 3) × 1016 cm−3 for the loose Fe2O3 powder and for pressed Fe2O3 powder pellets that are investigated for comparison. LIBS analysis of more than 20 different powder samples establishes calibration curves for Al, Si, Ni and Mn element impurities. The limits of detection derived from such curves are 8, 15, 66 and 860 ppm for Al, Si, Ni and Mn, respectively.

In-plane and out-of-plane resistivities of vicinal Hg-1212 thin films

Abstract Bi 2 Sr 2 Ca n −1 Cu n O 2( n +2)+ δ ( n =1,2,3) thin films are prepared on c -axis oriented and vicinal substrates by pulsed-laser deposition. Optimization of substrate temperature, laser fluence and post-annealing conditions produces single-phase, well-oriented and smooth films. The surface morphology, texture, crystallinity and stoichiometry of Bi 2 Sr 2 CaCu 2 O 8+ δ (Bi-2212) thin films strongly depend on the fabrication parameters. On ( 0 0 1 ) SrTiO 3 substrates, c -axis oriented Bi-2212 films with J c (60 K )=2×10 6 A/cm 2 and T c0 =82 K are obtained. Vicinal Bi-2212 films grown on miscut substrates reveal anisotropic resistivities independent of film thickness (20–300 nm), high J c anisotropy and strong in-plane and out-of-plane texture.