The structure and properties of the ferromagnet Tb(1-x)Dy(x)Fe(2) are explored through the morphotropic phase boundary (MPB) separating ferroic phases of differing symmetry. Our synchrotron data support a first order structural transition, with a broadening MPB width at higher temperatures. The optimal point for magnetomechanical applications is not centered on the MPB but lies on the rhombohedral side, where the high striction of the rhombohedral majority phase combines with the softened anisotropy of the MPB. We compare our findings with single ion crystal field theory and with ferroelectric MPBs, where the controlling energies are different.

We demonstrate a magnetoelectric nanocomposite, LiNbO3-CoFe2O4 (LNO-CFO), consisting of rhombohedral R3c LNO and R3m CFO phases. It is characterized by a maximum inverse magnetoelectric coefficient of 6.5 Oe cm·V−1 measured in a 106 V/m electric field, and a magnetic field dependent Vogel–Fulcher-like relaxation characterized by a relaxation time τ=τ0exp(−ΔH/k(Tm−TvfH)), τ0=29.66 s, ΔH=1.06 eV, TvfH represents the magnetic field-dependent Vogel-Fulcher temperature. The activation energy equals the activation energy of oxygen vacancy diffusion in niobate-based crystals. The room temperature electric field-induced magnetization change relaxes as τ=18.05 s.