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

Abstract

We report a simple, nondestructive B-H looper bending method for measuring 10/sup -7/ of magnetostriction (/spl lambda/) in thin films (/spl sim/150 /spl Aring/). The new method improves the accuracy and repeatability of /spl Delta/H/sub k/ measurements in loopers by employing a measurement sequence that corrects the non-repeatable balance errors. For the 150 /spl Aring/ thick NiFe films under an anisotropic strain of 4.6/spl times/10/sup -5/, we achieved a /spl Delta/H/sub k/ repeatability, 1/spl sigma/=0.009 Oe which is equivalent to 3.4/spl times/10/sup -8/ in /spl lambda/. Our technique gives /spl lambda/ 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 /spl lambda/.