Nanoscale dissipation and magnetoresistive1/fnoise in spin valves

Abstract

Spatial correlations of 1/$f$ noise in yoke-shaped, giant magnetoresistance spin valve sensors are reported. An upper bound of 135 nm, corresponding to a magnetic volume of 10${}^{5}$ nm${}^{3}$, is determined for the lateral size of the magnetic fluctuators responsible for the magnetoresistive 1/$f$ noise in regions where the resistance susceptibility is large. The normalized noise power is found to scale inversely with the separation between voltage taps along the arm of the yoke, also consistent with a local noise mechanism. The magnetoresistive 1/$f$ noise is associated with quasiequilibrium fluctuations in the micromagnetic structure having a length scale set by the disorder formed during the deposition and processing of the materials stack.