Fabrication and characterization of giant magnetoresistive elements with an integrated test coil

Magnetoresistive elements (MREs) containing exchange-biased spin valve multilayers as the magnetoresistive material have been fabricated. Their electrical response has been measured using an integrated test coil. Both parallel and crossed arrangements of the easy axes of the free and biased layers have been studied. Output voltage levels of these elements in response to an ac magnetic field are typically a factor of 7-10 higher than those obtained in similar elements based on a conventional, 30 nm thick anisotropic magnetoresistive (AMR) Ni₈₀ Fe₂₀ film linearized by the “barber-pole” method. The parallel arrangement is found to result in a switching behavior which is characteristic of domain wall movement and contains hysteresis, Barkhausen noise, and strong harmonic distortion. The arrangement with crossed anisotropies is found to display a behavior characteristic of switching by magnetization rotation as evidenced by a strong reduction of hysteresis, Barkhausen noise, and harmonic distortion. Demagnetization effects are calculated in order to quantitatively explain the shape of the response curve and the difference in output voltage when compared to AMR-based MREs