We report a large and nonvolatile bipolar-electric-field-controlled magnetization at room temperature in a Co40Fe40B20/Pb(Mg1/3Nb2/3)0.7Ti0.3O3 structure, which exhibits an electric-field-controlled looplike magnetization. Investigations on the ferroelectric domains and crystal structures with in~situ electric fields reveal that the effect is related to the combined action of 109\ifmmode^\circ\else\textdegree\fi{} ferroelastic domain switching and the absence of magnetocrystalline anisotropy in Co40Fe40B20. This work provides a route to realize large and nonvolatile magnetoelectric coupling at room temperature and is significant for applications.

We report a giant electric-field control of magnetization (M) as well as magnetic anisotropy in a Co40Fe40B20(CoFeB)/Pb(Mg1/3Nb2/3)0.7Ti0.3O3(PMN-PT) structure at room temperature, in which a maximum relative magnetization change (ΔM/M) up to 83% with a 90° rotation of the easy axis under electric fields were observed by different magnetic measurement systems with in-situ electric fields. The mechanism for this giant magnetoelectric (ME) coupling can be understood as the combination of the ultra-high value of anisotropic in-plane piezoelectric coefficients of (011)-cut PMN-PT due to ferroelectric polarization reorientation and the perfect soft ferromagnetism without magnetocrystalline anisotropy of CoFeB film. Besides the giant electric-field control of magnetization and magnetic anisotropy, this work has also demonstrated the feasibility of reversible and deterministic magnetization reversal controlled by pulsed electric fields with the assistance of a weak magnetic field, which is important for realizing strain-mediated magnetoelectric random access memories.

Since the revival of multiferroic laminates with giant magnetoelectric (ME) coefficients, a variety of multifunctional ME devices, such as sensor, inductor, filter, antenna etc. have been developed. Magnetoelastic materials, which couple the magnetization and strain together, have recently attracted ever-increasing attention due to their key roles in ME applications. This review starts with a brief introduction to the early research efforts in the field of multiferroic materials and moves to the recent work on magnetoelectric coupling and their applications based on both bulk and thin-film materials. This is followed by sections summarizing historical works and solving the challenges specific to the fabrication and characterization of magnetoelastic materials with large magnetostriction constants. After presenting the magnetostrictive thin films and their static and dynamic properties, we review micro-electromechanical systems (MEMS) and bulk devices utilizing ME effect. Finally, some open questions and future application directions where the community could head for magnetoelastic materials will be discussed.

Magnetoelectric (ME) heterostructures are widely studied to realize functional applications, such as magnetometers, ME random access memory (MERAM), ME antennas, energy harvesters, and voltage microwave devices. A good understanding of the nonlinearity of ME heterostructures can lead to potentially improved performance. Here, we present an investigation into the voltage-driven nonlinear phenomena of a ME heterostructure near its electromechanical resonance. The Stoner-Wohlfarth model and Duffing equation are used to study the ΔE effect in amorphous Metglas alloy and the nonlinear behavior of a ME heterostructure, respectively. Then, the dependence of the nonlinearity on bias field, driving voltage, mechanical quality factor, and the frequency sweeping direction are systematically studied and verified. Experimental results show that spring-hardening and -softening behavior is separately obtained at bias fields of 25 Oe and 50 Oe, respectively. In addition, hysteresis is observed when sweeping the frequency forward and then backward at a driving voltage of 5 V; this agrees well with qualitative analysis. This work provides a route to induce, control, and possibly exploit the nonlinear behavior of ME devices, such as magnetic-field energy harvesters and ME sensors and antennas.

Heterostructures were fabricated by growing ${\text{Pr}}_{0.6}{\text{Ca}}_{0.4}{\text{MnO}}_3$ (PCMO) films on $\text{Pb}{\left({\text{Mg}}_{1/3}{\text{Nb}}_{2/3}\right)}_{0.7}{\text{Ti}}_{0.3}{\text{O}}_3$ substrates. It was shown that the magnetizations of the samples can be tuned dramatically by electric fields via piezostrain and the effect is dominated by the change in phase separation. More interestingly, the electric-field control of magnetization is nonvolatile, manifesting a memory effect of strain. The results were discussed by considering the effect of electric-field-induced strain on the energy landscape of PCMO and the resultant change in phase separation. This work is helpful for exploring the evolution of phase separation with well-controlled strains and the magnetoelectric coupling effect.

Electric-field control of magnetism is significant for the next generation of large-capacity and low-power data storage technology. In this regard, the renaissance of a multiferroic compound provides an elegant platform owing to the coexistence and coupling of ferroelectric (FE) and magnetic orders. However, the scarcity of single-phase multiferroics at room temperature spurs zealous research in pursuit of composite systems combining a ferromagnet with FE or piezoelectric materials. So far, electric-field control of magnetism has been achieved in the exchange-mediated, charge-mediated, and strain-mediated ferromagnetic (FM)/FE multiferroic heterostructures. Concerning the giant, nonvolatile, and reversible electric-field control of magnetism at room temperature, we first review the theoretical and representative experiments on the electric-field control of magnetism via strain coupling in the FM/FE multiferroic heterostructures, especially the CoFeB/PMN–PT [where PMN–PT denotes the (PbMn_1/3Nb_2/3O₃)_1−x-(PbTiO₃)_x] heterostructure. Then, the application in the prototype spintronic devices, i.e., spin valves and magnetic tunnel junctions, is introduced. The nonvolatile and reversible electric-field control of tunneling magnetoresistance without assistant magnetic field in the magnetic tunnel junction (MTJ)/FE architecture shows great promise for the future of data storage technology. We close by providing the main challenges of this and the different perspectives for straintronics and spintronics.