Ba_0.85Ca_0.15Zr_0.1Ti_0.90O₃/CoFe₂O₄/Ba_0.85Ca_0.15Zr_0.1Ti_0.90O₃ Nanoscale Composite Films with 2–2\nConnectivity for\nMagnetoelectric Actuation

Abstract

Interfacial strain plays a vital\nrole in determining\nthe coupling\nstrength between the magnetic and electrically ordered phases in magnetoelectric\n(ME) nanostructures. The interfacial strain and its gradient size\nin a polycrystalline trilayer ME composite with a specific microstructure\nwere estimated by grazing incident X-ray diffraction (GI-XRD). The\naverage interfacial strain was estimated to have a maximum value of\n∼7%, and was found to be relaxed at a length scale of 25–35\nnm away from the interface. The optimized gradient size estimated\nfrom the trilayer ME composite was utilized to fabricate multilayers\nwith specific periodicities (“Δ”) and tested for\nthe inverse piezomagnetic effect to estimate the optimum periodicity\nrequired to have enhanced ME coupling. Multilayers with periodicity\n(∼40 nm) compared to multilayers with relaxed/partial interfacial\nstrain exhibited ∼25 to 26% increment in piezoelectric coefficient\n(<i>d</i>₃₃) in the presence of a magnetic field.\nThe constraint imposed on polarization by interfacial strain reflects\non the enhancement of stiffness and introduces a quicker linear response\nto the piezoelectric displacement. In contrast, the partially strained\nand/or strain-relaxed layers exhibited nonlinear responses in polarization\nswitching. The linear piezoelectric displacement in these strain-engineered\nME composites makes them a potential candidate for device applications\nlike actuators and transducers.