Magnetoelectric Composites: Applications, Coupling Mechanisms, and Future Directions

Abstract

Multiferroic (MF)-magnetoelectric (ME) composites, which integrate magnetic and ferroelectric materials, exhibit a higher operational temperature (above room temperature) and superior (several orders of magnitude) ME coupling when compared to single-phase multiferroic materials. Room temperature control and the switching of magnetic properties via an electric field and electrical properties by a magnetic field has motivated research towards the goal of realizing ultralow power and multifunctional nano (micro) electronic devices. Here, some of the leading applications for magnetoelectric composites are reviewed, and the mechanisms and nature of ME coupling in artificial composite systems are discussed. Ways to enhance the ME coupling and other physical properties are also demonstrated. Finally, emphasis is given to the important open questions and future directions in this field, where new breakthroughs could have a significant impact in transforming scientific discoveries to practical device applications, which can be well-controlled both magnetically and electrically.

Keywords: exchange bias; ferroelectricity; magnetism; magnetoelectric coupling; strain.

Figure 1

Various applications of magnetoelectric (ME) composites. Figures reproduced with permission from [9,39,40,41,43,44,45].

Figure 2

Schematic of (a) 0-3, (b) 2-2, and (c) 1-3 composite nanostructures.

Figure 3

Frequency dependence of (a) capacitance, (b) loss, (c) impedance, and (d) phase of PN2 composite at different static magnetic field. Figure reproduced with permission from [66].

Figure 4

(a) M-H loops at different external applied E-fields at RT (Inset: magnified M-H loop at high and low magnetic fields. (b) Variation of coercive field (H_c) (c) saturation magnetization (M_s) with external applied E-fields of PN2 composite (Arrows indicate the direction of E-field). Figure reproduced with permission from [66].

Figure 5

ME hysteresis loop at 100 K demonstrating the applied electric field dependence on the magnetic behavior of the PZT/La_0.7Sr_0.3MnO₃ (LSMO) heterostructure. The two magnetization values indicating the modulation of the magnetization values of LSMO layer (Insets: the FE and magnetic states of the PZT and LSMO layers respectively. The size of the white arrows implies the amplitude of magnetization qualitatively). Figure reproduced with permission from [54].

Figure 6

(a) Magnetic Field dependence of magnetization (M(H)) loops with and without electrical poling. (b) Capacitance as a function of frequency at different static H. (c) Z’ (real part of impedance) vs. Z’’ (imaginary part of impedance) plot at different H (solid line indicate the fitted data); the equivalent circuit used for fitting (inset). (d) Variation of bulk capacitance (C_b) and bulk resistance (R_b) at different H. Figure reproduced with permission from [22].

Figure 7

Magnetic field dependence of (a) dM/dH (b) M(dM/dH), and (c) dC⁻¹/dH of PC2 composite. Figure reproduced with permission from [22].