AMR, GMI & FMR measurements

The facilities available in our group offer the possibility to perform magnetoimpedance, magnetoresitance and other transport properties studies, i.e. observation of the change of a material electrical properties as a function of an external applied field. Of particular interest is the magnetoimpedance phenomenon in amorphous microwires, where a change of the impedance (Z) up to 600% of its original value was found in samples measured at high frequencies. Equipments are computer controlled so to perform systematic measurements of resistance (R), impedance (I), capacitance (C) and inductance (L) as a function of: external applied field (H) (0 – 10kOe), frequency (f (10kHz – 1MHz), current amplitude, V (1mV – 5V), temperature, T (4 – 300K). In addition, a home made pulley system, allows to perform magnetoimpedance and magnetoinductance studies with the sample under the action of an external applied tensile stress.

As a example here we show the correlation between magnetic domain structure (upper), magnetoimpedance response (middle) and hysteresis loop (below). A magnetostatic biased induced by the external layer induces a shift in the loop and originates the asymetric magnetoimpedance.

Another example is the anisotropic magnetoresistance observed in microwires in four different geometrical configurations (A, B, C and D), in which the electrical contacts are stablished at the ends of the microwires.

Ferromagnetic resonance studies are also performed in biphase microwires.

Back to Techniques»