Voltage control of magnetic single domains in Ni discs on ferroelectric BaTiO₃

Abstract

For 1 m-diameter Ni discs on a BaTiO 3 substrate, the local magnetization direction is determined by ferroelectric domain orientation as a consequence of growth strain, such that single-domain discs lie on single ferroelectric domains. On applying a voltage across the substrate, ferroelectric domain switching yields non-volatile magnetization rotations of 90°, while piezoelectric effects that are small and continuous yield non-volatile magnetization reversals that are non-deterministic. This demonstration of magnetization reversal without ferroelectric domain switching implies reduced fatigue, and therefore represents a step towards applications.Ferroelectric and ferromagnetic materials that are coupled via strain or exchange bias show large magnetoelectric effects at room temperature, and have therefore attracted considerable interest since the turn of the century [1][2][3][4][5]. For example, the heterostructures that display these magnetoelectric effects permit an applied electric field to switch individual magnetic domains [6], modify a large in-plane magnetization [7][8], switch a large magnetization from

Voltage-driven annihilation and creation of magnetic vortices in Ni discs

“…2(a-d The vortex state in the virgin disc was anisotropic, given that polar-plot lobes were oriented somewhat along x. For negative-magnetostriction Ni, this suggests the possibility of tensile strain along y. Polycrystalline films can indeed experience tensile growth strain from BTO substrates along the long c axis of a domains [17,45], possibly due to some degree of epitaxy.…”

“…1(a)]. Ni discs of this size are known to display vortices [35], whereas thinner Ni discs form single-domain states [35,45].…”

Interplay between morphology and magnetoelectric coupling in Fe/PMN-PT multiferroic heterostructures studied by microscopy techniques

“…In the (011) cut, application of an electric field 65 out of plane can effectively stabilize different in-plane strain 66 states at remanence [28]. This can be used to modify the 67 magnetic state of a film (or nanostructures) deposited on top 68 of it [29][30][31]. Considering shear strain, it has been shown that 69 a rotation of magnetization M by an angle of about 62°is 70 expected when the polarization P switches from out of plane 71 to in plane with a rotation of 71°or 109° [32].…”

XPEEM and MFM Imaging of Ferroic Materials

“…Reproduced with permission. [39] Copyright 2018, IOP Publishing. Red strips that extrapolate one species of a domain are a guide to the eye.…”

“…Sample cross-section appears in Figure3a, field of view has diameter 20 µm, green arrow represents IP projection of incident beam. Reproduced with permission [39]. Copyright 2018, IOP Publishing.…”