Converse Magnetoelectric Response Mechanism And Tunnel Magnetoresistance Effect Of Multiferroic Ferromagnetic/PMN-PT Heterostructure

With the advent of the era of big data,information storage has become the focus of people’s attention,among them,non-volatile random storage technology basedon magnetic tunnel junction（MTJ）plays an extremely important role.Therefore,the research of MTJ unit with magnetic random access memory device（MRAM）as the target device has become a research hotspot of spintronics.The traditional writing or readingof information by current or magnetic field can no longer meet the information revolution’s miniaturization of electronic devices,large capacity of circuit chips or high density of information storage.Therefore,seeking a new writing mechanism of information becomes one of the key challenges in developing new multifunctional spintronic components.Multiferroic composites can regulate the direction of magnetization through low-power voltage pulses rather than currents.In particular,the construction of ferromagnetic/piezoelectric artificial multi-iron heterojunctions can achieve strong magneto-electric coupling effects through effective mechanical strain transmission.If the piezoelectric effect is introduced into the design of the MTJ,the electric fieldor polarization charge is controlled by the tunnel magnetoresistance（TMR）effect,and the rich and complex lattice,spin,charge and orbital degrees of freedom are explored.The physics problem of coupling is not only of great theoretical value,but alsoa great promotion of MRAM application.In this paper,a La_0.7Sr_0.3MnO₃（LSMO）film was epitaxially grown on a Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃（PMN-PT）single crystal substrate oriented to（100）by pulsed laser deposition（PLD）.The variation of the magnetizationintensity of LSMO/PMN-PT heterojunction under different applied DC or AC voltages is studied,and the modulation mechanism is explored.Secondly,the variation of the magnetic resonance field of the heterojunction ferrite under different applied DC voltages is studied.The piezoelectric strain magnetic field displacement of the piezoelectric strain modulation reaches 170 Oe at 200 V.Finally,at a temperature of 10 K,the electric field-regulated TMR effect was achieved by applying a vertical film surface bias to the PMN-PT（100）single crystal substrate.TMR was observed to exceed-8%at a bias of 10 kV/cm,which is similar to the best record in the MTJ constructed in LSMO.It was first proposed that a similar TMR effect was observed in a single LSMO layer with PMN-PT as the substrate,and the spin-dependent transport brought about by complex structures was revealed.Next,a Ni thin film epitaxially grown on a（110）oriented PMN-PT single crystal substrate by magnetron sputtering.The variation of the magnetization of the Ni/PMN-PT heterojunction under different DC or AC voltages and its modulation mechanism are studied.The variation of the magnetic resonance field of the heterojunction ferrite under different applied DC voltages is also studied.The piezoelectric strain modulation of the lower piezoelectric strain is significantly changed,and the displacement reaches 600 Oe at 200 V.The above results have certain reference value for exploring the spin regulation mode of complex heterojunction,and also accumulated experimental basis for the application of multi-iron heterojunction in spintronic devices.