Stress-induced controllable magnetic properties in flexible epitaxial Mn_0.5Zn_0.5Fe₂O₄ ferrite films

Flexible ferrite film has high potential applications in electronic skins and wearable devices. However, it is an enormous challenge to fabricate flexible ferrite film because of its high fragility. This work uses a novel etching sacrificial Sr₃Al₂O₆ (SAO) layer to synthesize flexible Mn_0.5Zn_0.5Fe₂O₄ (MZFO) ferrite film. The MZFO film remains its single crystal structure after being transferred onto a flexible substrate. Owing to the great lattice mismatch between SAO and MZFO, the as-grown and transferred MZFO films exhibit the difference in magnetic properties, which is more sensitive along out-of-plane direction. The controllable magnetic properties of the film under the bending test are characterized by ferromagnetic resonance (FMR). A huge FMR field (H_r) shift of 704 Oe is achieved along out-of-plane direction when the bending radii are 5 mm. Meanwhile, the FMR linewidth (δH) of bent MZFO film (1267 Oe) is about 4 times higher than that of the unbent film (310 Oe). These controllable changes mainly come from the contribution of the two magnon scattering (TMS) effect. Finally, the H_r and δH almost return to their initial states when the stress is released, indicating a great recoverability.