Large magnetoelectric effect from mechanically mediated magnetic field-induced strain effect in Ni–Mn–Ga single crystal and piezoelectric effect in PVDF polymer

Magnetoelectric (ME) effect is observed in a bilayered composite fabricated by laminating one ferromagnetic shape memory Ni–Mn–Ga single-crystal plate with one piezoelectric PVDF polymer film. The reported ME effect originates from the mechanically mediated magnetic field-induced strain effect in the Ni–Mn–Ga plate and piezoelectric effect in the PVDF film. The induced ME voltage shows a good linear response to the applied ac magnetic field in the field range of 0–5 Oe. A large ME coefficient (αE) of 1.24 V/(cm Oe) is obtained at an optimal bias magnetic field of 5.1 kOe due to the reversible reorientation of martensitic twin variants in the Ni–Mn–Ga plate. Based on the combination of pseudo-piezomagnetism in the Ni–Mn–Ga plate and piezoelectricity in the PVDF film, the ME effect in the bilayered composite is predicted and found to agree with the experimental results.