A Novel Broadband Measurement Method for the Magnetoimpedance of Ribbons and Thin Films

A novel broad-band measurement method of the MI in thin films and ribbons is presented. It is based on the automated measurement of the reflection coefficient of a cell loaded with the sample. Illustrative results obtained with a permalloy multilayer thin film are presented and discussed.Comment: Paper submitted to International Conference on Magnetism (Rome 2003

Magnetic and Transport Properties of NiFe/SiO_{2}/NiFe Trilayers

Magnetic coupling between Ni_{81}Fe_{19} double thin films separated by an insulating SiO_{2} spacer layer is investigated with structural measurements, cross sectional imaging, magnetization measurements (BH loop) and transport under the conditions of variable spacer thickness ranging from 0 to 5000 Angstroms. We investigate several models to explain the coercivity variation with spacer thickness as well as the transport measurements.Comment: Digest accepted in INTERMAG Europe 2002 (Amsterdam). Full paper submitted to IEEE Trans. Magnetic

Metal-to-glass ratio and the Magneto-Impedance of glass-covered CoFeBSi microwires at high frequencies

High frequency [1-500 MHz] measurements of the Magneto-Impedance (MI) of glass-covered Co$_{69.4}$Fe$_{3.7}$B$_{15.9}$Si$_{11}$ microwires are carried out with various metal-to-wire diameter ratios. A twin-peak, anhysteretic behaviour is observed as a function of magnetic field. A maximum in $\Delta Z/Z$ appears at different values of the frequency $f$, 125, 140 and 85 MHz with the corresponding diameter ratio $p$ = 0.80, 0.55 and 0.32. We describe the measurement technique and interpret our results with a thermodynamic model that leads to a clearer view of the effects of $p$ on the maximum value of MI and the anisotropy field.Comment: 5 pages and 6 figure