System for measuring magnetostriction employing a plurality of external magnetic field rotation harmonics

Abstract

A system for measuring the magnetostriction coefficient λ of a sample material applied to a substrate element fixed at one end leaving the other end free to be deflected. An external rotating magnetic field of rotation frequency f and intensity Hext is applied to the cantilever substrate element the amplitude Am of the deflection of the free end is measured at each of a plurality of rotation frequency harmonics {fm} by, for example, using a plurality of lock-in amplifiers. The harmonic deflection amplitudes {Am} are combined to determine the magnetostriction coefficient λ of the sample material. At an Hext equal to the sample saturation moment Msat and assuming a 15 Oe sample anisotropy Hk and coupling bias Hp, the error in the saturation magnetostriction coefficient λS measured according to this invention may be reduced by 80% to 90% over the error seen when using only the second harmonic deflection amplitudes A2.

Dependencies are inferred from the claim text.