METHOD FOR DETERMINING BOTH MAGNETOSTRICTION AND ELASTIC-MODULUS BY FERROMAGNETIC-RESONANCE

The magnetostriction constant lambda(s) includes a combination of both elastic constants c(ij) and magnetoelastic coupling constants B(i). To provide information on both c(ij) and B(i), a method for measurement of both lambda(s) and the elastic modulus Y of thin films has been developed using ferromagnetic resonance (FMR). As in prior FMR schemes for measuring lambda(s), a strain is produced in the film by bending the substrate, and the resulting anisotropy field is measured. However, by using a triangular polymer beam as a substrate, three important advantages are obtained (i) the triangular beam shape has uniform strain along its surface, (ii) the polymer material supports large strains (>10(-3)) without breaking, and (iii) the low elastic modulus of the beam allows measurement of the sample elastic modulus through variation of the sample aspect ratio. Measurements on Ni foils yield values of lambda(s) and Y which fall within the scatter of literature data.