Ultraflexible and Malleable Fe/BaTiO₃ Multiferroic Heterostructures for Functional Devices

The high demand for flexible spintronics based on multiferroic heterostructures makes growing high-quality flexible, functional oxides urgently, in which needs to be deposited on lattice-matched substrates. In this paper, ultraflexible and malleable iron (Fe)/BaTiO₃ (BTO) multiferroic heterostructures are demonstrated, showing a perfect crystallinity and hetero-epitaxial growth. In terms of performance, they indicate good multiferroic properties and excellent bending tunability, as well as obvious magnetoelectric (ME) coupling effect. During the phase transformation from the rhombohedral phase to the orthorhombic phase of BTO layers in the heating process, a large ME coupling coefficient of 120 Oe °C⁻¹ along the out-of-plane direction is obtained. This value keeps consistent in the phase-field simulation of magnetic domain evolution, in which the biaxial compressive strain induced-magnetoelastic anisotropy facilitates the magnetic easy axis of Fe layers to the [110] or [–1–10] direction. Besides, ultraflexible Fe/BTO heterostructures are found to have a 690 Oe ferromagnetic resonance (FMR) field shift along the out-of-plane direction under the flexible tuning (R = 5 mm). This work should pave a way toward flexible spintronic and functional devices with fast speed, portability, and low energy consumption.