Manipulations of the coercivity and the Kerr signal of the NiFe films by a ZnO underlayer

In this study, Ni50Fe50 films with different thicknesses were prepared on a ZnO(0001) film that was grown on a conductive Si(100) substrate. The ZnO(0001) film was characterized to be a ferroelectric layer with a value of piezoelectric constant, d33, equal to 5.0pm/V. Monotonic decreases in the coercivity of the NiFe films can be observed while the ZnO layer exposed to an electric field. As the applied potential equal to 10V, the coercivity of the NiFe films reduced 64% and 41% for the thickness equal to 10nm and 50nm, respectively. The strength of the strain field established inside the NiFe films was strongly correlated with the decreasing ratio of the coercivity. Moreover, the Kerr signal of the NiFe films can be well modulated by the electric fields established across the ZnO layer while the potential lower than 10V. The lattice distortion and dislocation formation inside the ZnO layer controlled the highest potential that can be applied and, consequently, the reliability of the modulation of the Kerr signal.