Giant magnetoimpedance in trilayer structures of patterned magnetic amorphous ribbons

We have measured the giant magnetoimpedance (GMI) and giant magnetoresistance (GMR) of Metglas®/Cu/Metglas trilayer stacks of micropatterned amorphous magnetic Metglas 2714a ribbons and Cu foils. We obtain room-temperature GMI ratios [Z(0)−Z(Hs)]/Z(Hs) up to 800%, and GMR ratios [R(0)−R(Hs)]/R(Hs) up to 2400% at frequencies of 100 kHz–10 MHz, with Hs the magnetic field in which impedance and resistance saturate towards their minimum values. These high values are a direct consequence of the large dynamic relative permeability of the magnetic ribbons and the chosen trilayer geometry. We analyze our results in the context of a theoretical model of L. V. Panina and K. Mohri [Sens. Actuators A 81, 71 (2000)].