Magnetostriction in spin valves

We report an accurate method for the measurement of the saturation magnetostriction lambda(s) of thin conducting ferromagnetic films using spin valve structures. We describe an alternative to the cantilever beam method, called the bending method, which utilizes the inverse magnetostrictive effect. Typical soft ferromagnetic films exhibit hysteretic magnetization loops, which make the measurements of the magnetoelastic energy (hence lambda(s)) imprecise or erroneous. We show how to resolve the hysteresis problem by application of a transverse field. We also demonstrate the quantitative connection between the cantilever and bending method in a comparative study of films spanning a large magnetostriction range. The sensitivity of measurement of magnetostriction using the bending method is better than 1 x 10(-7). (C) 1999 American Institute of Physics. [S0021-8979(99)79508-3].