Reversible magnetoelectric switching in multiferroic three-dimensional nanocup heterostructure films

Abstract

Self-assembled nanocomposite films containing ferroelectric and ferromagnetic phases have attracted enormous research interest because they are the most promising candidates for practical multiferroic applications. However, obtaining a genuine magnetoelectric (ME) coupling effect is still challenging in this research area. To substantially improve the ME effect, new heterostructure designs with efficient strain control between two phases are urgently needed. Herein, a novel three-dimensional (3D) nanocup architecture of a heterostructure film is developed. To establish the unique architecture, a heavily Co, Fe-doped ferroelectric Bi 3.25 La 0.75 Ti 3 O 12 (BLT) target was used during the growth of BLT thin films via pulsed laser deposition. Consequently, 3D nanocup-structured CoFe 2 O 4 (CFO) particles formed inside the BLT via spontaneous nucleation and agglomeration. The 3D nanocup BLT-CFO film exhibited magnetically controlled reversible dielectric switching, which is direct evidence of strong ME coupling caused by the efficient interfacial strain coupling and low leakage of the novel nanocup architecture. The obtained results strongly suggest that the 3D nanocup heterostructure film significantly improves the ME coupling effect. In addition, we propose a new paradigm in the architecture design of self-assembled nanocomposite films for diverse multifunctional devices.

Self-Assembled Hexagonal Lu1–xInxFeO3 Nanopillars Embedded in Orthorhombic Lu1–xInxFeO3 Nanoparticle Matrixes as Room-Temperature Multiferroic Thin Films for Memory Devices and Spintronic Applications

“…The AFM and TEM data therefore unequivocally show the formation of a self-assembled “double-epitaxial” nanostructure consisting of tapered h - LIFO nanopillars in the o-LIFO matrix. In conventional self-assembled nanocomposite films containing ferromagnetic and ferroelectric phases, a composite target with a specific molar ratio of ferroelectric and ferromagnetic materials was needed, containing two immiscible oxides such as BFO–CFO, BTO–CFO, , and PTO–CFO with cube-on-cube relationships as well as BFO–NFO and BLT–CFO with Stranski–Krastanov relationships, although there are reports on single-phase self-assembled distorted cubic materials that exhibit two or more variants with a mosaic structure, such as orthorhombic LaFeO 3 , , SrRuO 3 , and tetragonal PbTiO 3 films, or double-epitaxial growth in SrTi 0.7 Co 0.3 O 3−δ and SrTi 1– x Fe x O 3 , films. However, ferromagnetism and ferroelectricity cannot coexist.…”

Tunable Magnetism and Morphology of Ferromagnetic Nanocups in Perovskite Ferroelectric Films via Co Exsolution of Transition Metals

“…In BLCFT thin films, strained and relaxed BLT phases coexist (Figure d–f). We predicted that this strained BLT phase resulted from an increased BLT lattice constant at the interfaces with CFO, which has a larger lattice constant . Most notably, the separated magnetic phase (Co 3 O 4 , antiferromagnetic; CFO, ferromagnetic) can be observed only in the Co-doped BLT, and Co,Fe-codoped BLT thin films, except for the Fe-doped BLT.…”

“…Previously, we demonstrated the possible formation of multiferroic three-dimensional (3D) Bi 3.25 La 0.75 Ti 3 O 12 (BLT)-CoFe 2 O 4 (CFO) nanocup films that employ a heavily Co,Fe-doped BLT target . The unique nanocup films exhibit reversible magnetoelectric switching at room temperature, owing to the spontaneous segregation of CFO nanocups during epitaxial thin film growth, which resembles exsolution trends.…”

Magnetoelectric Composites of P(VDF-TrFE)/Porous-Ni for Electrostatic Air Filters

“…By applying an external DC magnetic field ( H dc ) to the ME composites, magnetostrictive materials are mechanically deformed, and thereafter, the mechanical deformation is transferred to piezoelectric materials as mechanical stress, leading to the induction of electrical displacement in piezoelectric materials. , The ME composites exhibited meaningful PM capture performance with a high carbon/fluorine molar ratio of 7.01, as determined by energy-dispersive X-ray (EDX) analysis under an applied H dc of 700 Oe, indicating the feasibility of the ME effect on PM removal. However, the following requirements must be met to improve the surface charge in ME composites: (i) high coupling between the piezoelectric and magnetostrictive phases, (ii) low leakage current during the poling process, and (iii) optimization of polymeric phase conformation. − …”