Electric Field-mediated Exchange Bias Of Magnetic Thin Film

The exchange bias field of ferromagnetic/anti-ferromagnetic system has rich physical significance and important application value in GMR devices.With the development of spintronic devices,it is more and more urgent to control the exchange bias,and the regulation of magnetic field provides a new idea,which provides a possibility for the realization of new spintronic devices with low energy consumption,high efficiency and non-volatility.In ferromagnetic/ferroelectric multiferroic heterostructures,the magnetoelectric coupling enhances the intensity of magnetic field regulation,which has attracted more attention from researchers.In this paper,magnetron sputtering is used to prepare ferromagnetic/anti-ferromagnetic system with exchangebiasontheferroelectricsinglecrystalssubstrateof Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃?PMN-PT?,the static vibration sample magnetometer,dynamic ferromagnetic resonance and electric transport are used to measure the ferromagnetic/anti-ferromagnetic system under the action of electric field.The results are as follows:?1?The ferromagnetic/anti-ferromagnetic system was prepared by magnetron sputtering,and the influence of anti-ferromagnetic layer of different thickness on exchange bias was studied.Using S-W model of free energy of the system under different electric fields,including uniaxial magnetic anisotropy,unidirectional magnetic anisotropy and stress anisotropy,with the change of the ratio between uniaxial magnetic anisotropy and unidirectional magnetic anisotropy regulated by the electric field,realize electric field control 180°magnetization switching,which provides a possibility for multi-state memory storage.?2?The dynamic ferromagnetic resonance is used to measure the size of non-volatile exchange bias in a weak exchange bias system.Co/IrMn ferromagnetic/antiferromagnetic samples with weak exchange bias were prepared by magnetron sputtering on PMN-PT ferroelectric single crystal substrates.The ferromagnetic resonance was used to measure the change of the resonance field along direction of magnetic easy and difficult axis respectively with the electric field to obtain the asymmetric butterfly curve,and it was non-volatile at zero electric field.The angle dependence of the resonance field were measured under different electric field,is obtained by fitting formula free energy of the ferromagnetic resonance uniaxial anisotropic effective field and exchange bias field along with the change of the electric field is asymmetric butterfly curve,this is consistent with the stress curve of ferroelectric basal,shows that magnetic field regulation mechanism is dominant strain effect.?3?The electric field controlled non-volatile exchange bias field and multi-state magnetic storage are realized in a ferromagnetic material?CoFeB?with large magnetoelastic coefficient,the electric field-controlled the ratios of the uniaxial magnetic anisotropy field and the unidirectional magnetic anisotropy field are obtained and achieve electric field control 180°switching of magnetization.In the absence of an external magnetic field,a stable non-volatile multiple remanent state is obtained by different electric field scanning methods and changes of the pulsed electric field,which provides an experimental basis for multi-state magnetic storage;The angle dependence of the resonance field under different electric fields is tested by ferromagnetic resonance.The angle dependence of the resonance field under different electric fields is obtained by the free energy formula.The uniaxial and unidirectional magnetic anisotropy with the electric field are both asymmetric,the change of non-volatile 180^ounidirectional magnetic anisotropy were achieved.