Study of magnetoelectric coupling in magnetoelectric laminates fabricated using 15-mode PMN-PZT single crystals

Piezoelectric coefficients d_ij and g_ij, the key parameters of the piezoelectric constituent of magnetoelectric (ME) composites, strongly influence their ME coupling. Considering this fact, we adopted three different types of piezoelectric materials with different crystallographic orientations, namely, 31-, 32-, and 15-mode PMN-PZT single crystals, to fabricate ME laminates. ME laminates can be easily fabricated using 31- and 32-mode PMN-PZT crystals, but it is difficult to fabricate them using 15-mode PMN-PZT because of the challenges in generating the 15-shear mode. In this study, 15-shear mode ME laminates were fabricated by sandwiching 15-mode PMN-PZT single crystals between Metglas and Ni, both of which exerted opposing magnetostrictive stresses on the 15-mode PMN-PZT to generate two-sided shear vibrations in it. Prior to the fabrication, the number of Metglas layers was optimized, owing to its differing thickness from that of Ni, to generate equal magnetostriction at the same applied DC magnetic field. ME laminates fabricated using two-layer (2L) and three-layer (3L) Metglas exhibited a maximum ME voltage coefficient (α_ME) of 0.04 V/cm Oe. In contrast, the α_ME values of ME laminates fabricated using 31- and 32-mode PMN-PZT single crystals were 0.46 V/cm Oe and 1.45 V/cm Oe, respectively, much higher than that of the 15-mode ME laminate. The small ME coupling in the 15-mode ME composite can be attributed to the unideal shear mode generated in the ME laminate.