Flexible Heteroepitaxy of CoFe₂O₄/Muscovite Bimorph with Large Magnetostriction

Abstract

A bimorph composed of ferrimagnetic cobalt ferrite (CoFeO, CFO) and flexible muscovite was fabricated via van der Waals epitaxy. The combination of X-ray diffraction and transmission electron microscopy was conducted to reveal the heteroepitaxy of the CFO/muscovite system. The robust magnetic behaviors against mechanical bending were characterized by hysteresis measurements and magnetic force microscopy, which maintain a saturation magnetization (M) of ∼120-150 emu/cm under different bending states. The large magnetostrictive response of the CFO film was then determined by digital holographic microscopy, where the difference of magnetostrction coefficient (Δλ) is -104 ppm. The superior performance of this bimorph is attributed to the nature of weak interaction between film and substrate. Such a flexible CFO/muscovite bimorph provides a new platform to develop next-generation flexible magnetic devices.

Atomic Scale Understanding of the Epitaxy of Perovskite Oxides on Flexible Mica Substrate

“…For perovskite SrRuO 3 film system, the crystallographic orientation relationship between films and mica substrate was determined as {111} films || (001) mica and 〈01〉 films || [010] mica by X‐ray diffraction (XRD) . The similar orientation relationships have also been observed for spinel oxide films on mica . Electron microscopy imaging and electron diffraction analysis confirmed the orientation relationships.…”

“…Very recently, intensive research has been devoted to such epitaxial growth of functional perovskite and spinel oxides films on mica for flexible devices . For perovskite SrRuO 3 film system, the crystallographic orientation relationship between films and mica substrate was determined as {111} films || (001) mica and 〈01〉 films || [010] mica by X‐ray diffraction (XRD) .…”

Van der Waals oxide heteroepitaxy

“…Typically, three-or six-fold axis with the lowest surface energy will be the orientation of epitaxial film on muscovite. In most oxide epitaxial systems on muscovite, the lattice constants and properties were shown to be 34 The lattice parameters were found to be very close to bulk, indicating a mitigation of the strain. Since CoFe 2 O 4 is a magnetostrictive material, it was found that the magnetostrictive coefficient is very close to the single crystal value, suggesting a lack of substrate clamping.…”

“…Thus, there is no misorientation control of vdW oxide heteroepitaxy, implying an Fig. 2 A summary on the current status of vdW oxide heteroepitaxy 31,34,[36][37][38][39][40] Van der Waals oxide heteroepitaxy Y-H Chu important research direction since the anisotropic property is a key feature in most epitaxial thin film system. (4).…”

Light Tuning of the Resistance of NdNiO3 Films With CoFe2O4 Capping

“…Therefore, clamping effect could be easily removed by providing energy to the NNO atoms through electromagnetic radiation. Moreover we are believing CFO is a flexible material that could allow the NNO structural transition from orthorhombic to monoclinic at the interface and as a result increase in resistance was observed. Besides, CFO capping prevents the abrupt structural change in NNO likely due to the clamping effect, resulting in the slow resistance variation.…”