| The magnetoelectric(ME) coupling exsisting at the interface between the ferroelectrics(FE) and ferromagnets(FM) lays a reliable foundation for us to exploit new multi-field-controlled components of spintronics which are expected to be lowenergy-consumed and(FE/FM)-highly-integrated, however, the coupling mechanisms behind still need further investigation: the ME coupling dominated by the exchange-bias and strain effect respectively are indirect couplings and belong to bulk effect, which can be completely suppressed under certain conditions; the interfacial electric field(E-field) effect is generally a direct ME coupling, though it is usually considered to be weak and short-ranged. In this thesis, we through detailed analysis reveal that the nontrivial vertical electric polarization will induce excitation of the low-energy coherent spin waves in the FM subsystem adjacent to the FE/FM interface, leading to a spiral magnetic order with definite chirality in the vicinity of FM interface; whereby we achieve a strong direct linear ME coupling whose range is as far as nanometers, via which we fully controll the dynamical revolution of the magnetization electrically: procession and relaxation.Experimentally, we realize the electric-field-based tuning of the effective magnetic field and damping in the fabricated polycrystal CoZr/PMN-PT samples, showing a electrically-controlled magnetic dynamical behavior which is in excellent consistance with our theoretical analysis. |
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