Electric-field Control Of Magnetoelectrical Transport Properties In Multiferroic H Ete Rostructu Res

The devices based on multiferroic heterosturctures and their magnetoelectric coupling effects are applicable in the following two main fields:one is in the field of microwave devices,including electric-field tunning sensors,detectors,phase shifters,etc.;another one is in the field of a variety of electronic and spintronic devices,such as energy harvesting devices,memory devices,signal processors,drivers,and so on.There are mainly three mechanisms of electric-field controlling of magnetism,as the following:the modulation mechanism of exchange bias effect,the modulation mechanism of interface charge,and the regulation mechanism of strain effect.The controlling mechanism of strain effect has attracted extensive attentions.Based on the controlling mechanism of strain effect,the single-layer ferromagnetic thin film and magnetic tunnel junction on ferroelectric materials heterojunction are investigated in this essay.The magnetoelectrical transport properties of the Ni81Fe19(NiFe)ferromagnetic stripe/Bi3.15Nd0.85Ti2.99Mn0.01O12(BNTM)ferroelectric thin film combined hetero?junction was modulated by an electric field at room temperature.Firstly,we deposited good-quality BNTM thin films on Pt(111)/Ti/SiO2/Si(100)substrates by a sol-gel method.After that,we fabricated NiFe stripe devices by micro-nano fabrication processing.By applying an electric field to the BNTM film bringing about a strain effect,the NiFe stripe device's magnetoresistance was changed,and ferromagnetic resonance spectrum was shifted and deformed.Spin-orbit torque in the system was malipulated by the electric field applied to the ferroelectric thin film,the spin orbit torque ratio(?a:?b,field-like torque:damping-like torque)was changed,the torque ratio(?a/?b)changes approximately 0.07.From the result of experiment,the piezoelectric coefficient is calculated to be 332 fJ/Vm.Furthermore,the magnetoelectrical transport properties of the CoFeB/MgO/CoFeB magnetic tunnel junctions on PMN-PT piezoelectric substrate was modulated by a strain effect.Firstly,we fabricatied the CoFeB/MgO/CoFeB magnetic tunnel junctions on PMN-PT piezoelectric substrate by magnetron sputtering and micro-nano fabrication.Then the strain which is generated by applying a vertical electric field to the PMN-PT substrate modulated the magnetoelectrical transport properties of the devices,as follows:(1)The electric field modulated the magnetoresistance curve of the magnetic tunnel junctions,the magnetoresistance curve changed sharp switching to slanted one,the reason is that the magnetization direction of the free layer changes along the direction of the easy axis of the free layer to the direction of the hard axis;(2)Under a zero magnetic-field,the dependence of resistance and the applied electric field to the substrate was hysteresis;(3)The ferromagnetic resonance of the magnetic tunnel junctions was modulated by an electric field,the resonance peak of the ferromagnetic resonance spectrum has be shifted,the electric field modulation ability is 145 MHz·cm kV-1 under the negative electric field.