[en] The permeability spectra of a multiferroic heterostructure composed of a FeCoZr thin film grown onto a [Pb(Mg_1_/_3Nb_2_/_3)O_3]_0_._6_8-[PbTiO_3]_0_._3_2(011) (PMN-PT) substrate are characterized as a function of an electrical field applied through the thickness of the substrate. When the sample is in an unpoled state and the applied electrical field is increased from 0 kV cm"−"1 to 2 kV cm"−"1, the resonance frequency remains relatively the same. However, as the electrical field is increased beyond 2 kV cm"−"1, the resonance frequency is drastically increased from 2.17 GHz to 3.28 GHz and the peak of the permeability spectra becomes much broader. When the electrical field is further increased from 2 kV cm"−"1 to 6 kV cm"−"1, the resonance frequency is gradually increased and finally reaches 4 GHz. As the electrical field is reduced from 6 kV cm"−"1 back to 2 kV cm"−"1, the resonance frequency is reduced in the same manner, and the peak disappears when the electrical field is reduced to less than 2 kV cm"−"1. These behaviors are discussed in terms of the magnetization rotation and magnetic anisotropy dispersion based on the stress distribution of the piezoelectric substrate as a function of the applied electrical field. This argument is consistent with the hysteresis loops measured before and after poling. The result suggests that the electrical tunability of the magnetization rotation in multiferroic heterostructures can be employed to electrically turn on and off the microwave operation of the materials, which is promising for applications. (paper)