Giant magnetoimpedance strip and coil sensors

We present noticeable values of giant magnetoimpedance on a cobalt-rich amo rphous alloy, together with a new approach to giant magnetoimpedance device s of reduced size. Values as high as 260% of impedance variation as a funct ion of the applied magnetic field are obtained with the samples in the usua l form of long ribbons. The benefits of specific thermal treatments in reac hing these high values are studied through the magnetic domain structure. I n order to reduce the size of the system and therefore extending the practi cal use of giant magnetoimpedance devices, we present the results obtained in wound ribbons in the form of coils. Though the magnetoimpedance is consi derably reduced, it is still large enough to be applicable in sensor device s. (C) 2001 Elsevier Science B.V. All rights reserved.