Large E-field tunability of microwave ferromagnetic properties in Fe ₅₀Co₅₀-Hf/lead zinc niobate-lead titanate multiferroic laminates

Fe₅₀Co₅₀-Hf films were deposited on the (011)-cut single crystal lead zinc niobate-lead titanate (PZN-PT) substrates by a composition gradient sputtering (CGS) method. Strong converse magnetoelectric (ME) coupling was observed in the multiferroic laminates of CGS Fe ₅₀Co₅₀-Hf/PZN-PT, which exhibited a large electric field (E-field) tunability of microwave magnetic properties. With the increase of E-field strength from 0 to 8 kV/cm, the ferromagnetic resonance (FMR) fields H_r shifted upwards by 270.2 Oe and downwards by 237.7 Oe along hard axis and easy axis directions, being equivalent to 33.8 and 29.7 Oe cm/kV, respectively. Accordingly, the self-biased ferromagnetic resonance frequency f_FMR significantly enhanced from 4.0 to 6.5 GHz with an increment of Δf_FMR 2.5 GHz under a zero-bias magnetic field, and the magnetic damping constant α decreases from 0.0280 to 0.0185. The strong ME coupling between CGS Fe₅₀Co₅₀-Hf film and PZN-PT substrate not only enhanced the f_FMR but also reduced the magnetic loss at microwave frequencies, which gives great opportunity in fabrication of tunable microwave devices.