Ferroelectric relaxor-PbTiO₃ single crystal based magnetoelectric composites and devices

Magnetoelectric (ME) composites exhibit robust ME interfacial coupling due to strong interaction between piezoelectricity and magnetostriction. The presence of two novel functionalities i.e., direct ME coupling, magnetic field control of ferroelectric polarization, and converse ME coupling, electric field control of magnetization makes them ideal candidates for multifunctional devices such as energy harvesters, magnetic field sensors, ME random access memories, ME antennas, etc. The ME coupling in these ME composites is strongly dependent on the superior physical properties of the piezoelectric and magnetostrictive materials. Therefore, magnetostrictive materials with excellent piezomagnetic coefficients and piezoelectric materials with excellent piezoelectric coefficients are desired to achieve large ME coupling. Among piezoelectric materials, ferroelectric relaxor-PbTiO₃ (PT) single crystals have been extensively used as a piezoelectric constituent due to their ultrahigh piezoelectric and electromechanical properties. In addition, the domain structure and crystal orientation of the relaxor-PT single crystals exhibit extraordinarily large piezoelectric and electromechanical properties. Due to those multifunctional properties, relaxor-PT single crystal-based ME composites were widely used to study direct and converse ME couplings in ME composites in recent days. Relaxor-PT single crystal-based ME composites indeed showed excellent ME coupling, for instance, the highest ME voltage coefficient, equivalent magnetic noise, and output power of 7000 Vcm^-1Oe^-1 @ 23.23 kHz, 6pT//√Hz @1 Hz and 19 mW @ 60 Hz, respectively which are one of the best-reported values so far in ME composites. Considering the vast research on relaxor-PT single crystal-based ME composites, here we present a detailed review on recent trends in ME composites and ME devices based on relaxor-PT single crystals.