GMI low frequency noise characterization versus wire diameters

Equivalent magnetic noise levels at 1 Hz of three GMI samples have been experimentally determined for different excitation conditions related to both dc current and ac excitation amplitude. These three wires or cylindrical-shaped samples are from the exact same alloy composition and obtained from the same fabrication process. The only difference is their diameter which are 80 im, 100 im and 120 im, since this parameter has been identified as an important factor involved in GMI low frequency noise level. Indeed, from the recently proposed model, briefly reminded here, the equivalent magnetic noise level should decrease with the square of the wire diameter. These low frequency equivalent magnetic noise level measurements have been conducted with coherence measurements showing that the main noise source responsible of this noise level is the intrinsic noise of the GMI sensor. Obtained results have then been compared to the expected noise level from the theoretical model, showing a relative good agreement, validating the behavior regarding wire diameter.