RESUMEN
The ultrahigh flexibility and elasticity achieved in freestanding single-crystalline ferroelectric oxide membranes have attracted much attention recently. However, for antiferroelectric oxides, the flexibility limit and fundamental mechanism in their freestanding membranes are still not explored clearly. Here, we successfully fabricate freestanding single-crystalline PbZrO3 membranes by a water-soluble sacrificial layer technique. They exhibit good antiferroelectricity and have a commensurate/incommensurate modulated microstructure. Moreover, they also have good shape recoverability when bending with a small radius of curvature (about 2.4 µm for the thickness of 120 nm), corresponding to a bending strain of 2.5%. They could tolerate a maximum bending strain as large as 3.5%, far beyond their bulk counterpart. Our atomistic simulations reveal that this remarkable flexibility originates from the antiferroelectric-ferroelectric phase transition with the aid of polarization rotation. This study not only suggests the mechanism of antiferroelectric oxides to achieve high flexibility but also paves the way for potential applications in flexible electronics.
RESUMEN
HIGHLIGHTS: The (001)-oriented ferromagnetic La0.67Sr0.33MnO3 films are stuck onto the (011)-oriented ferroelectric single-crystal 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 substrate with 0° and 45° twist angle. By applying a 7.2 kV cm-1 electric field, the coexistence of uniaxial and fourfold in-plane magnetic anisotropy is observed in 45° Sample, while a typical uniaxial anisotropy is found in 0° Sample. Manipulating strain mode and degree that can be applied to epitaxial complex oxide thin films have been a cornerstone of strain engineering. In recent years, lift-off and transfer technology of the epitaxial oxide thin films have been developed that enabled the integration of heterostructures without the limitation of material types and crystal orientations. Moreover, twisted integration would provide a more interesting strategy in artificial magnetoelectric heterostructures. A specific twist angle between the ferroelectric and ferromagnetic oxide layers corresponds to the distinct strain regulation modes in the magnetoelectric coupling process, which could provide some insight in to the physical phenomena. In this work, the La0.67Sr0.33MnO3 (001)/0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 (011) (LSMO/PMN-PT) heterostructures with 45º and 0º twist angles were assembled via water-etching and transfer process. The transferred LSMO films exhibit a fourfold magnetic anisotropy with easy axis along LSMO < 110 >. A coexistence of uniaxial and fourfold magnetic anisotropy with LSMO [110] easy axis is observed for the 45° Sample by applying a 7.2 kV cm-1 electrical field, significantly different from a uniaxial anisotropy with LSMO [100] easy axis for the 0° Sample. The fitting of the ferromagnetic resonance field reveals that the strain coupling generated by the 45° twist angle causes different lattice distortion of LSMO, thereby enhancing both the fourfold and uniaxial anisotropy. This work confirms the twisting degrees of freedom for magnetoelectric coupling and opens opportunities for fabricating artificial magnetoelectric heterostructures.
RESUMEN
The rapid development of spintronics requires the devices to be flexible, to be used in wearable electronics, and controllable, to be used with magnetoelectric (ME) structures. However, the clamping effect inevitably leads to a decreased ME effect on the rigid substrate, and it remains challenging to directly prepare high-quality ferroelectric (FE) membranes on the widely used flexible substrate such as MICA or polyimide (PI). Here, periodic wrinkle-patterned flexible (Co/Pt)5/BaTiO3 (BTO) perpendicular magnetic anisotropy (PMA) heterostructures were prepared using the water-soluble method. The high-quality single-crystal BTO membrane ensures that intricate wrinkles do not fracture and a high ME coefficient is achievable. The transferred sample that is released from the clamping effect shows an enhanced ME effect in both in-plane and out-of-plane directions, with the ME coefficient reaching up to 68 Oe °C-1. The ferromagnetic resonance (FMR) field of the flexible sample can be tuned by tensile strain up to 272 Oe. The finely controlled wrinkle shows periodic strain variations at peak and valley regions that switch the PMA magnetic domain motion as an effective control method. The proposed ultraflexible wrinkle sample shows great potential for combining multiple magnetization tuning approaches, allowing it to potentially serve as a tunable high-density 3D storage prototype.