Enhancement of magnetoresistance in [Pd∕Co]N∕Cu∕Co∕[Pd∕Co]N∕FeMn spin valves

Abstract

The dependences of the stack number and Co and Cu thicknesses on magnetoresistance, and perpendicular exchange biasing in the [Pd∕Co]×N1∕Cu∕Co∕[Pd∕Co]×N2∕FeMn spin valves, were investigated. The magnetoresistance ratio of the spin valves with N1=4 and N2=2 was above 5% for the Cu between 1.5 and 2.5nm, and the exchange-biasing field (Hex) was increased to 600Oe. When the Co thickness over the Cu layer was increased from 0.48to1.28nm, the ratio likewise rose to 7.4% due to the strengthened spin-dependent scattering effect. Moreover, the Co thickness below the Cu layer rose to 9.1%. The maximum ratio of 10.2% was obtained in the structure of the [Pd0.8∕Co0.32]×2∕Pd0.8∕CoFe0.48∕Cu2.25∕CoFe0.6∕[Pd0.8∕Co0.48]×2∕FeMn15 (nanometer) multilayer with Hex=450Oe.

Improved magnetoresistance through spacer thickness optimization in tilted pseudo spin valves based on L1 (111)-oriented FePtCu fixed layers

“…For the thinnest spacer ͑0.8 nm͒ we observe about 2% MR, which rapidly increases with Cu spacer thickness to a maximum value of around 5% at t Cu = 2.4 nm, and then again decreases for thicker Cu spacer. We note that this thickness dependence is similar to what is observed in in-plane and out-of-plane spin valves [14][15][16] and pseudo spin valves. 17,18 We also extract the overall sample resistance ͑R͒ in the parallel state taken from the value measured at Ϫ14 kOe applied field.…”