High precision magnetostriction measurement employing the B-H looper bending method

We report a simple, nondestructive B-H looper bending method for measuring 10^-7 of magnetostriction (λ) in thin films (~150 Å). The new method improves the accuracy and repeatability of ΔH_k measurements in loopers by employing a measurement sequence that corrects the non-repeatable balance errors. For the 150 Å thick NiFe films under an anisotropic strain of 4.6×10^-5, we achieved a ΔH_k repeatability, 1σ=0.009 Oe which is equivalent to 3.4×10^-8 in λ. Our technique gives λ values that agree well with the optical cantilever bending technique and can be easily utilized in a thin-film head production environment for accurate control of λ