Ultrathin high anisotropic magnetoresistance Ni0.81Fe0.19 films

We have fabricated an ultrathin high anisotropic magnetoresistance (AMR) Ni0.81Fe0.19 (10.0 nm) film grown on a (Ni0.81Fe0.19)0.63Cr0.37 (5.5 nm) underlayer with dc magnetron sputtering. The AMR value (ΔR/R) and the coercivity of the film attain 1.61(6)% and 178 A m-1 (i.e. 2.2 Oe), respectively. The ΔR/R of (Ni0.81Fe0.19)0.63 Cr0.37(5.5 nm)/ Ni0.81Fe0.19(10.0 nm) film has increased by ∼34% over that of Ta(5.4 nm)/Ni0.81Fe0.19(10.0 nm) film (ΔR/R = 1.20(6)%) prepared using the same magnetron sputtering. The results of x-ray diffraction and atomic force microscopy show that the underlayer of (Ni0.81Fe0.19)0.63 Cr0.37 makes it easier to promote the formation of Ni0.81Fe0.19(111) texture and dramatically improves the crystalline grain size in the columnar direction and the average surface grain size of the Ni0.81Fe0.19film. The result of x-ray photoelectron spectroscopy shows that the (Ni0.81Fe0.19)0.63Cr0.37 underlayer, unlike the traditional Ta, does not react with the Ni0.81Fe0.19 film at the interface