Measurement of Anisotropy and Magnetoelastic Constants of Thin Crystalline Films by Angle- and Strain-Dependent Ferromagnetic Resonance Spectroscopy

Anisotropy and magnetoelastic constants of a magnetostrictive film can be determined by measuring the ferromagnetic resonance (FMR) in the film as a function of applied magnetic field and strain. In previously reported such measurements, only the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$B_{1}$ </tex-math></inline-formula> magnetoelastic constants were determined. We adapt the technique to also measure <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$B_{2}$ </tex-math></inline-formula> (or shear-dependent) magnetoelastic constants by designing instrumentation to apply a uniform bending moment to the sample along different crystalline axes to obtain both tensile and shear strains in the film. Knowledge of magnetoelastic constants is indispensable to enabling multiferroic and magnetoacoustic devices. <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$B_{2}$ </tex-math></inline-formula>, in particular, is relevant to magnetoacoustic devices where significant shear strain can be induced by the acoustic waves. Using the technique described herein, we determine the anisotropy and magnetoelastic constants for epitaxial NiZnAl-ferrite films of application interest due to their high magnetostriction and low magnetic damping. The <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$B_{1}$ </tex-math></inline-formula> constant is found comparable to values published elsewhere while <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$B_{2}$ </tex-math></inline-formula> is determined for the first time.