Substrate clamping effect onto magnetoelectric coupling in multiferroic BaTiO ₃ -CoFe ₂ O ₄ core-shell nanofibers via coaxial electrospinning

Abstract

We report large lateral magnetoelectric (ME) coupling coefficients α31 of 1.2 × 10 4 mV cm −1 Oe −1 and 3.5 × 10 4 mV cm −1 Oe −1 in substrate bonded and free-standing multiferroic BaTiO3-CoFe2O4 (BTO-CFO) core-shell nanofibers (NFs) with and without substrate clamping effect, respectively. The BTO-CFO core-shell NFs were synthesised by a sol-gel coaxial electrospinning technique, and their ME coupling was directly observed by demonstrating the evolution of piezoelectric coefficient (d33), ferroelectric domain, and phase contrast induced by an external magnetic field. These impressed α31 coefficients originated from the nanoconfinement of the interphase elastic interaction between the ferromagnetic core fiber and the ferroelectric shell interlayer, as well as the strain transformation at the one-dimensional (1D) fiber boundary. This means that the decreasing substrate clamping effect results in an enhanced ME coupling in multiferroic NFs, which is similar to that of thin films. These findings make people understand the substrate clamping effect and enable nanoscale ME device applications.

Magnetoelectric coupling in CoFe2O4‐Pb(Zr0.2Ti0.8)O3 coaxial nanofibers

“…CoFe 2 O 4 (CFO)-Pb(Zr 0.52 Ti 0.48 )O 3 , CFO-BiFeO 3 and CFO-BaTiO 3 core-shell NFs 2,8,9 have been prepared and confirmed their ME coupling. Most of the previous reports focused on the magnetic field control of the polarization in ME NFs by detecting the piezoelectric response change under an external magnetic field, indicating magnetic-field induced ferroelectric polarization switching.…”

“…Most of the previous reports focused on the magnetic field control of the polarization in ME NFs by detecting the piezoelectric response change under an external magnetic field, indicating magnetic-field induced ferroelectric polarization switching. 2,[8][9][10] While seldom works has focused on the magnetic-field induced electric order change, 3,11 especially in nanoscale though the converse ME effect also provide the opportunity to realize novel devices in electric field-tunable radiofrequency/microwave signal processing, magnetic field sensor, and ultralow power logic-memory, etc. [12][13][14] Therefore, it is of significance to qualitatively and quantitatively estimate the converse ME coefficients at nanometer length scale.…”

Attempts to obtain BaTiO3/Fe2O3 core-shell type structures: The role of iron oxide nanoparticle formation and agglomeration

“…Thin films are usually grown up on a substrate, and effect of substrate clamping cannot be neglected. This is mainly because substrate clamping influences ferroelectric phase, which may affect ferromagnetic phase, in way that decreases magnetoelectric coupling coefficient for couple orders of magnitude [18]. Further, the core/shell structure has the advantage that one phase completely surrounds another phase, which can introduce a strong strain at the interface [19].…”

Hybrid Magnetoelectric Nanowires for Nanorobotic Applications: Fabrication, Magnetoelectric Coupling, and Magnetically Assisted In Vitro Targeted Drug Delivery

“…This value is in the same order as those reported for some other 1D core–shell nanostructures (e.g., CoFe 2 O 4 @PbZr0 .52 Ti 0.48 O 3 , CoFe 2 O 4 @BaTiO 3 , CoFe 2 O 4 @BiFeO 3 ) evaluated by similar methods. [13a,19] However, it should be noted that such local measurements cannot be compared directly to the macroscopic ME coefficient, although some recent theoretical analysis indicates that composite multiferroic nanowires could potentially exhibit a ME response orders of magnitude higher than that of thin films with similar compositions …”