High magnetostriction metallic glasses used as magnetoelastic labels

High-magnetostriction Fe-rich metallic glasses in the form of ribbons present a magnetoelastic resonance characterized by the frequency of the longitudinal vibrational mode of the sample, ω _r, which is a function of the applied static field, H. This value of ω_r can be used to recognize different objects or the position of a single object in a field gradient, that is as a carrier of information. To test these applications we have studied an amorphous alloy of composition Fe_60.8Co_16.2Si_12.2B_10.8 with saturation magnetostriction λ_s=33×10^-6 and spontaneous magnetization J_s=1.46 Tesla. Samples were used both in as-quenched state and after transverse field annealing. Initially measurements were performed by detecting simultaneously different resonant peaks in different samples. Resonance frequency values, frequency ratios and magnitude of detected signals are discussed. The convenience of detecting different resonant peaks on a single sample with a “fixed point” is also shown