Investigation Of Some Related Effect In Perovskite Manganites Based On The Resistive Switching

The perovskite manganites are a kind of typical strongly correlated materials and have become one of the hottest topics in condensed matter physics due to their colossal magnetoresistance,high spin polarizability and large magnetic entropy changes.This system is also a kind of resistance switching materials which exhibit the high and low resistance states under the application of voltage.Due to the correlation between their electric and magnetic properties,the perovskite manganites provide a good platform for the study of the voltage control of magnetism and show important applications in the fields of low-power spin-electronics devices and others.In this dissertation,we study the effect of resistance switching on magnetoresistance,magnetoelectric properties and magnetic refrigeration effect of perovskite manganites.The main content and conclusions are as follows:1.Multilevel resistance switching effect in Au/La2/3Ba1/3MnO3/Pt heterostructure manipulated by external fieldsPerovskite manganites play an important role in the application of low energy consumption information storage since they can show good resistance switching effect.In order to obtain multilevel resistance states and improve the memory density,we investigate the control of resistance states in this system by multiple physical fields.The La2/3Ba1/3MnO3(LBMO)film is deposited on an(111)-oriented Pt/Ti/SiO2/Si substrate by pulsed laser deposition(PLD).The bipolar resistance switching effect with good retention is realized in this Au/LBMO/Pt device.Then we study the effect of magnetic field on resistance switching and find that the remarkable magnetoresistance effects are observed both in the high and low resistance states of LBMO.Under the coaction of electric field and magnetic field,four resistance states with excellent repeatability are achieved in this device,and can be switched between any two states.Therefore,by combining the resistance switching and magnetoresistance effects,we achieve four resistance states in the Au/LBMO/Pt device,which provides a feasible plan for improving the storage density.2.Tuning phase transition and magnetoresistance of La0.7Sr0.3MnO3 film by voltageIn the study of controlling the magnetic properties of perovskite manganites based on the resistance switching effect,the high resistivity is generally required.Due to the correlation between the electric and magnetic properties,these films usually exhibit weak magnetism,which is not beneficial to the application in spintronic devices.In order to solve the problem of mutual restriction between electric field control of magnetism and the resistance switching effect in a single layer perovskite film,we study the effect of resistance switching effect of CeO2 on phase transition temperature and magnetoresistance(MR)of La2/3Sr1/3MnO3(LSMO).In the LSMO/CeO2/Pt device,CeO2 exhibits a bipolar and stable resistance switching behavior.Taking advantage of the migration of oxygen vacancies of CeO2,the magnetic properties of LSMO can be manipulated.The experimental results show that in the high resistance state,the saturated magnetization(Ms)and MR of LSMO film increase and the ferromagnetic-paramagnetic transition temperature(Tc)shifts to the high temperature.In the low resistance state,the Ms and MR decrease while the Tc shifts to the lower temperature.These results provide a new way for the development of low-power and multifunctional spintronics base on the perovskite manganites.3.Nonvolatile Control of Magnetocaloric Operating Temperature by Low VoltageThe limited operating temperature is the main obstacle for the practical applications of magnetic refrigeration.In the current research on electric field manipulation of the refrigeration temperature region,a few hundred volts of voltage is generally need and this type of manipulation is usually volatile,which are disadvantageous for the practical applications.In this chapter,we investigate the non-volatile control of the refrigeration temperature region in LSMO under low voltage.The films of CeO2 and LSMO are sequentially deposited on the Pt/Ti/SiO2/Si substrate by PLD.In the CeO2,a bipolar resistance switching effect with 103 ratio is observed.By switching between the high and low resistance states,the curie temperature and the Ms of LSMO are remarkably changed.In both high and low resistance states,the LSMO exhibits large magnetocaloric effect and the peak temperature of the magnetic entropy change varies from 305 K and 315 K.In this way,we realize the non-volatile control of the refrigeration temperature region in LSMO by low voltage,which has potential applications in wide-temperature-region magnetic refrigeration.