| Multiferroic materials allow the realization of the magnetization change by an external electric field and vice versa.The magnetic structure variation driven by an electric input?electric field or current?has been proposed in broad and bright aspects regarding the potential applications in spintronics.Compared with conventional elec trical current,electric-field manipulation of magnetization has some significant advantages,including miniaturization,high efficiency,low energy consumption and multi-functionalization.In this paper,Fe3O4/Pb(Mg1/3Nb2/3)O3-PbTiO3?PMN-PT?and NiFe/PMN-PT have been produced separately by pulsed laser deposition and magnetron sputtering,and the static and dynamic magnetization state of multiferroic heterostructure was investigated under external electric field.In addition,the mechanism of magnetoelectric coupling effect was explained at the interface between ferroelectric and ferromagnetic.Fe3O4?125 nm?thin films were deposited on PMN-PT?001?single crystal by pulsed laser deposition.The smooth and uniform surface of Fe3O4/PMN-PT?001?multiferroic heterostructure was prepared by reasonably optimizing parameters such as growth temperature,deposition oxygen pressure,frequency and energy.The temperature dependence and angular dependence of Fe3O4/PMN-PT?001?were analyzed by SQUID and EPR.The change process of static and dynamic magnetization state under external electric field was observed by MOKE.Both Hc and Mr/Ms reached a maximum value of 358 Oe and 95%,respectively,and the body spin-wave resonance mode appeared at the Verwey transition temperature?Tv=120 K?.Besides,the resonance mode of transition occurs at critical angle 82°.A piezoelectric substrate 0.70Pb(Mg1/3Nb2/3)O3-0.30PbTiO3?PMN-PT?with different lateral piezoelectric coefficients with d31=-1750 pC/N?along[100]direction?and d32=900pC/N?along[011]direction?is chosen to construct composite multiferroic heterostructure with Fe3O4 thin films.The magnetic properties of the Fe3O4/PMN-PT?011?were investigated by MOKE and EPR.The lattice constant of Fe3O4 increased by 0.08%after polarization,the coercive field decreased from 368 Oe to 113 Oe,the variation of Mr/Ms was 30%,and the displacement of Hr was as high as-483 Oe.In addition,the change of ferromagnetic resonance field from 251 Oe to 9681 Oe by simultaneously applying an external electric field and a rotating sample along axes perpendicular to the magnetic field.NiFe film was prepared on a PMN-PT?001?single crystal substrate by an ultra-high vacuum magnetron sputtering apparatus to form a NiFe/PMN-PT multiferroic heterostructure.The surface and cross-section microscopic appearance of NiFe/PMN-PT were observed by SEM and AFM.The magnetic properties of NiFe/PMN-PT were analyzed by SQUID and EPR.The MOKE and the EPR were used to investigate the dynamic and static changes of the magnetic field under the electric field,and the mechanism of the reverse magnetoelectric effect was revealed.The hysteresis loop changes significantly at the vicinity of the coercive electric field value of the PMN-PT single crystal substrate.The hysteresis loop has little change when it is far from the Hc. |
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