Giant magnetoimpedance in tri-layer structures of patterned magnetic amorphous ribbons

We have measured the giant magnetoimpedance (GMI) and giant magnetoresistance (GMR) of Metglas®/Cu/Metglas trilayer stacks of micropatterned amorphous magnetic Metglas 2714a ribbons and Cu foils. We obtain roomtemperature GMI ratios [Z(0)-Z(Hs)]/Z(Hs) up to 800 % and GMR ratios [R(0)- R(Hs)]/R(Hs) up to 2400 % at frequencies of 100 kHz-10 MHz, with Hs the magnetic field where impedance and resistance saturate towards their minimum values. These high values are a direct consequence of the large dynamic relative permeability of the magnetic ribbons and the chosen trilayer geometry. We analyze our results in the context of a theoretical model of L. V. Panina and K. Mohri [Sens. Actuators A 81, 71 (2000)]

Epitaxial multilayers of YBa2Cu3Ox/PrBa2Cu3Ox/YBa2Cu3Ox

Heteroepitaxial multilayers of YBa2Cu3Ox/PrBa2Cu3Ox/YBa2Cu3Ox have been made by sputtering. No degradation of the transition temperature and the critical current density due to the presence of the PrBa2Cu3Ox layer could be observed. By using high-resolution transmission electron microscopy the atomic details of the interfaces and the defect structures have been studied. These films showed a perfectly stacked lattice just above the interface between film and substrate. The orientation of the c-axis perpendicular to the substrate was fairly perfect. The structural faults are mainly distributed in the middle and overlying layers. The dominant defects in our films seems to be stacking faults which give rise to nano-sized coherent anti-phase domains with the 1-2-3 structure. Rutherford backscattering spectroscopy, secondary ion mass spectroscopy, and scanning Auger microscopy were used to examine the interdiffusion between layers. Within the experimental resolution of 7 nm no interdiffusion is visible between YBa2Cu3Ox and PrBa2Cu3Ox layers

Fabrication of a novel microsystem for the electrical characterisation of cell array

We have designed and realised a new type of microsystem for the electrical characterisation of arrays of living cells for biomedical diagnostic purposes. We have used deep plasma etching for the fabrication of microholes and micro-fluidic channels in silicon substrates. After oxidation and electrical contact fabrication, these structured silicon wafers have been anodically bonded with Pyrex wafers. The fabrication is completed by the gluing of micro-patterned polyimide foils on top of the silicon. We have tested the electrical characteristics of our microsystems using NaCl salt solutions of various molarities. We believe that our device will open new perspectives for biochemical sensor applications

Limits on deviations from Onsager-Casimir symmetry in the resistance of YBaCuO

Wetensch. publicatieFaculteit der Wiskunde en Natuurwetenschappe

Development of a Novel Printed Circuit Board Technology for Inductive Device Applications

This paper describes the fabrication and characterisation of 2-dimensional inductive devices integrated inside printed circuit boards . PCB and flex-foils. These devices basically are composed of three layers of which the outer layers bear the printed coil patterns and the inner layer is a high permeability ferromagnetic sheet core. Both magnetic metal and copper layers are patterned using standard lithographic techniques. Electroplated interconnections between the outer layers complete the windings. We have fabricated both transformers and fluxgate magnetic field sensing devices with a thickness of 200 mm for the flex-foil devices and 600 mm for the PCB-based devices. Lateral dimensions are approximately 1 cm. We realise relatively high inductances of 1–10 mH at a frequency of 1 kHz for the transformers and a magnetic field detection limit of 43 mT at 20 kHz for the fluxgate devices