Giant magneto-impedance in heterogeneous microwires
Recent results concerning the giant magneto-impedance effect, GMI, in magnetic microwires having diameter in the range of a few micrometers and heterogeneous character are introduced in this work. Two types of microwires have been studied, namely, (i) magnetic microwires covered by insulating Pyrex glass coating and (ii) copper wires covered by electrodeposited magnetic microtubes. The magnetic anisotropy distribution in each type of microwire is correlated with giant magneto-impedance. While the main source of anisotropy in glass coated microwires is of magnetoelastic origin created by the stresses induced during quenching and by the coating, in the case of the microtubes the origin is the columnar growth during the electrodeposition. The influence on GMI of various treatments that modify the anisotropy is analyzed. Heterogeneous microwires with different thicknesses of insulating coating and of magnetic tube are analyzed.
Magnetic Properties of Heusler-Type NiMnGa Glass-Coated Microwires
In this paper, we studied the magnetic properties of the Heusler-type NiMnGa glass-covered microwires. We observed that annealing conditions strongly affect the temperature dependence of magnetization and Curie temperature of microwires. After long (6 h) annealing of the microwires at 773 K, a ferromagnetic ordering is obtained with Tc ≈ 300 K, which is beneficial for a magnetic solid-state refrigeration.
Electrodeposited amorphous Co-P alloys with high permeability
Abstract Uniaxial magnetic anisotropy of electrodeposited amorphous Co-P alloys is included during preparation of the material. The direction of the easy axis depends on the arrangement of the electrodes. Tube-shaped samples with a circumferential easy direction and maximum permeabilities up to 106 and coercivities of about 50 mOe can be produced by the use of a rotating cathode.