*3.1.5 ME coupling in Ce, La-substituted BFTO*

The longitudinal ME coupling coefficient, αME is measured for Ce and La-doped BFTO and shown in **Figure 4(c)**. The samples are biased with *ac* magnetizing field, Hac = 10 Oe at 1093 Hz, and a *dc* magnetic field, Hdc is applied collinear to it. The value of αME was determined as a function of *dc* magnetic field using: αME = \_\_\_ <sup>∂</sup>*<sup>E</sup>* ∂*H* = \_1 *t* \_\_\_ ∂*V* ∂*H* = \_\_\_\_\_\_ *<sup>V</sup>*out *<sup>t</sup>* <sup>×</sup> *<sup>H</sup>*ac. In **Figure 4(c)**, the value of αME increases rapidly to a maximal value (due to an enhancement of elastic interactions) and then slowly decreasing in the higher region of Hdc. The maximum value of αME (mV cm<sup>−</sup><sup>1</sup> Oe<sup>−</sup><sup>1</sup> ) is 62.65 and 49.79, respectively, for BFTO:Ce and BFTO:La.
