Epitaxial ferromagnetic manganite films have been sputtered on bicrystal substrates. Their magnetoresistance was measured as a function of magnetic field and temperature. The grain boundary magnetoresistance at low temperature is separated from the intrinsic magnetoresistance near the Curie temperature. The grain boundary magnetoresistance peaks at about 100 Oe and saturates at about 2 kOe. For a La0.8Sr0.2MnO3 film with a grain boundary angle θ=36.8° a field independent component r0=4.1×10−6 Ω cm2 was separated from a field-dependent component which has its maximum rH=2.3×10−6 Ω cm2 for H of order the coercive field.
By direct imaging we determine spin structure changes in Permalloy wires and disks due to spin transfer torque as well as the critical current densities for different domain wall types. Periodic domain wall transformations from transverse to vortex walls and vice versa are observed, and the transformation mechanism occurs by vortex core displacement perpendicular to the wire. The results imply that the nonadiabaticity parameter does not equal the damping , in agreement with recent theoretical predictions. The vortex core motion perpendicular to the current is further studied in disks revealing that the displacement in opposite directions can be attributed to different polarities of the vortex core.
Epitaxial ferromagnetic La0.8Sr0.2MnO3−δ films have been sputtered on SrTiO3 bicrystal substrates. Etched patterns crossing the bicrystal grain boundary are compared with identical patterns not crossing it. The films were annealed at different conditions and their magnetoresistance measured as a function of temperature T and of in plane magnetic field H strength and direction. Annealing at 900 °C was found to modify the grain boundary and to increase its magnetoresistance. For H=±80 Oe parallel to the grain boundary and T=32 K narrow magnetoresistance peaks of 60% height are measured. They are interpreted in the frame of an in plane magnetotunneling structure.
We developed a Raman-compatible chip for isolating microorganisms from complex media. The isolation of bacteria is achieved by using antibodies as capture molecules. Due to the very specific interaction with the targets, this approach is promising for isolation of bacteria even from complex matrices such as body fluids. Our choice of capture molecules also enabled the investigation of samples containing yet unidentified bacteria, as the antibodies can capture a large variety of bacteria based on their analogue cell wall surface structures. The capability of our system is demonstrated for a broad range of different Gram-positive and Gram-negative germs. Subsequent identification is done by recording Raman spectra of the bacteria. Further, it is shown that classification with chemometric methods is possible.
High-quality Tl 2 Ba 2 CaCu 2 O 8 films for microwave filter application are prepared on both sides of 2 inch lanthanum aluminate substrates as well as on double-sided CeO 2 coated r-cut sapphire substrates. The films have thicknesses as high as 1 µm in the case of lanthanum aluminate substrates. On CeO 2 buffered sapphire substrates it is possible to prepare crack-free superconducting films as thick as 400 nm. For both substrate materials we reach high critical current densities of J c > 2 × 10 6 A cm −2 at 77 K. The microwave surface resistances R s were measured to fall short of 100 µ at 5.6 GHz and 77 K in the low-field case, comparable to the best films made of YBa 2 Cu 3 O 7−x material. The films were able to tolerate high microwave power levels corresponding to magnetic field amplitudes of B RF > 2 mT. The critical temperature exceeds 102 K. This excellent performance is maintained even after several thermal cycles. The films were used to produce four-pole band-pass filters for the C-band which were operated without any detectable loss in their transfer characteristics up to temperatures of about 85 K. This is the first time that large area (2 inch) double-sided Tl 2 Ba 2 CaCu 2 O 8 films have been prepared on sapphire with excellent critical current density in conjunction with low surface resistance.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.