Light,Electric,Magnetic Field Modulation And Stress Effect Of N-type Hafnium-doped Manganese Oxide Thin Films And Heterojunctions

Due to the strong correlation between spin,charge and orbital degrees of freedom,perovskite transitional metal oxide materials exhibit extremely rich and novel physical phenomena,such as metal-insulator transition,phase separation,and large magnetoresistance effect.The quantum states of the manganese oxides with similar free energies have led to the competition and coexistence of multiple metastable states,the manganese oxide which are significantly sensitive to the physical field.In this paper,the perovskite manganese oxide material La_0.9Hf_0.1MnO₃?LHMO?was chose as the research object to investigate the electrical transport properties of thin films and heterojunctions under the tuning effect of light,electric,magnetic and stress field systematically.The details are as follows:1?The LHMO thin films were prepared on the SrTiO₃?001?substrate by pulsed laser deposition technique with different annealing pressures and annealing times.The effect of annealing conditions on the electrical transport properties was investigated.The results show that increasing the annealing oxygen pressure and prolonging the annealing time will improve the metal insulation transition temperature of the film.2?The effect of lattice mismatch on the electrical transport properties was investigated in the LHMO thin films.Substrates with different lattice constants enable to provide different stresses.The SrTiO₃?STO?,LaAlO₃?LAO?,?LaAlO₃?_0.3?Sr2AlTaO₆?_0.7?LSAT?,KTaO₃?KTO?and?Zr,Y?O₂?YSZ?single crystal substrate are selected for obtaining the thin fims,respectively.It has been found that stress can reduce the metal-to-insulation transition temperature of the film,which affects the electrical transport properties of the material.3?The change of electrical transport properties of LHMO film under the modulation of stress and light fields was studied.Under the control of the light field,the photoresist effect of the film appeared,and the photoresistivity under the two kinds of different stresses was compared,and it was found that the photoresist effect under the compressive stress was obvious.4?With the influence of the magnetic field,the magnetic transport properties of electronic-conductive film and hole-conductive film were compared.LHMO and La_0.8Ba_0.2MnO₃?LBMO?films were prepared on LSAT substrates,respectively.LHMO film is electronic conductive,LBMO film is hole conductive.It was found that both the electronically conductive film and the hole-conductive thin film,the magnetic field underthe resistance of the film will increase with the magnetic field becomes smaller,and at a certain temperature of the film has a maximum porosimagnetic resistivity.5?The properties of LHMO / 0.05 wt% Nb-SrTiO₃?NSTO?heterojunction are studied,including the rectifying effect and photoelectric effect.At the same time,the rectifying effect of heterojunctions is studied under multi-field regulation such as light,electric and magnetic fields.The results show that the reverse current and forward current under the multi-field modulation are larger,heterojunction show better rectifier characteristics.