A phenomenological thermodynamic theory is used to investigate the effect of external mechanical stress on the magnetoelectric coupling in ferroelectric PbTiO3 or organic P(VDF-TrFE)/ferromagnetic Terfenol-D heterostructures. The results showed that the effects of external stress on the value of polarization strain sensitivity and magnetoelectric (ME) polarization coefficient for PbTiO3 and P(VDF-TrFE) are opposite, in which the electrostrictive constants play a significant role. However, the external stress has similar influence on the value of ME voltage coefficient in the two heterostructures. The compressive stress increases their ME voltage coefficient, and a peak appears near the stress of 200 MPa, in qualitative agreement with the experiment result. It is proposed that external stress might provide a new way to enhance or adjust magnetoelectric coupling in multiferroic heterostructures.
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The list of the parameters used in the calculations (in SI units, the temperature T in K). For PbTiO3: ; ; ; ; ; ; . For P(VDF-TrFE) 65:35, ; ; ; ; ; ; . For Terfenol-D, = 1300 ppm; = 0.8T; = 80; = 200 MPa; = 110 GPa.
