Colossal magnetoelectric effect in 3-1 multiferroic nanocomposites originating from ultrafine nanodomain structures

Abstract

We investigate colossal magnetoelectric coupling through interactions between ferroelectric and ferromagnetic nanodomains in 3-1 multiferroic BaTiO3/CoFe2O4 nanocomposites using a recent real-space phase field model based on the Landau-Ginzburg theory. A hierarchical ultrafine domain structure is characteristically formed in the nanocomposites, resulting in an extremely high density of domain walls, which causes polarization domains to be more susceptible to an external magnetic field via interfacial strain-mediation. This leads to an anomalously large magnetoelectric coupling effect in the multiferroic nanocomposites. We further demonstrate that the domain configuration and consequent magnetoelectric effect are strongly dependent on the constituent phase distribution, suggesting a promising route for the rational design of multiferroic domains and magnetoelectric effects, reminiscent of recent nano-metamaterial concepts.

Understanding and designing magnetoelectric heterostructures guided by computation: progresses, remaining questions, and perspectives

“…79 In the field of magnetoelectric heteorstructures, effective magnetoelectric coupling coefficients have been evaluated or predicted by effective medium theories, 80 87,88 and by phase-field simulations. [89][90][91][92][93][94] Note that phase-field method can predict the co-evolution of the microstructure (grain/domain structure) and its corresponding effective (linear 89,92 and nonlinear) 90,91,93,94 magnetoelectric coupling coefficients under externally applied fields. Notably, Ni et al 89 proposed a phase-field method to identify the optimum phase morphology in piezomagnetic-piezoelectric composites that lead to a maximum linear direct magnetoelectric coupling coefficient.…”

Magnetoelectricity in vertically aligned nanocomposites: Past, present, and future

“…In ME VANs consisting of square-shaped CFO rods embedded in a BTO matrix, PF reveals that, while domain structures within rods are relatively simple, hierarchical ultrafine nanodomains are formed in the ferroelectric matrix (see Fig- ure 2c). 67 There is thus an extremely high density of domain walls that are susceptible to an externally applied H, leading to a high ME effect (see Figure 2d). 67 It has also been shown that, with maintaining the shapes and volume fraction of magnetic rods, the distribution of constituent phase, or the geometrical arrangement (square, honeycomb, and triangular arrays) of rods, strongly affects the final domain configuration (domain wall density) and thus the ME coefficient.…”

“…67 There is thus an extremely high density of domain walls that are susceptible to an externally applied H, leading to a high ME effect (see Figure 2d). 67 It has also been shown that, with maintaining the shapes and volume fraction of magnetic rods, the distribution of constituent phase, or the geometrical arrangement (square, honeycomb, and triangular arrays) of rods, strongly affects the final domain configuration (domain wall density) and thus the ME coefficient. 67 PF can also be used to simulate ME VANs with periodically aligned cuboid-shaped CFO inclusions embedded in a BTO matrix.…”

“…67 It has also been shown that, with maintaining the shapes and volume fraction of magnetic rods, the distribution of constituent phase, or the geometrical arrangement (square, honeycomb, and triangular arrays) of rods, strongly affects the final domain configuration (domain wall density) and thus the ME coefficient. 67 PF can also be used to simulate ME VANs with periodically aligned cuboid-shaped CFO inclusions embedded in a BTO matrix. 68 By changing the aspect ratio, r = c/a, of the cuboids, the effects of phase connectivity on the ME coefficient can be systematically considered.…”

Sequential piezoresponse force microscopy and the ‘small-data’ problem

“…[37][38][39][40] On the other hand, modeling predicts complex domain evolution in composites. [41][42][43] PFM based investigation (direct ME effect) is expected to reveal a strong modulation of the local piezoresponse (i.e., polarization) as a function of the externally applied magnetic field [20][21][22][23][24][25][26][27][28] giving an indirect insight into the spatial distribution of the local magnetoelectro-mechanical interactions.…”