Large E-field tunability of microwave ferromagnetic properties in Fe50Co50-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 Fe50Co50-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 Hr 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 fFMR significantly enhanced from 4.0 to 6.5 GHz with an increment of ΔfFMR = 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 fFMR but also reduced the magnetic loss at microwave frequencies, which gives great opportunity in fabrication of tunable microwave devices.