Structuralanalysis And Physical Property Study Of Doped SrIrO₃ Perovskite

Transitional metal oxides crystallized as perovskite phase exhibit a large number of strange physical behaviors,such as giant magnetoresistance,high temperature superconductivity and polyferroic,which have attracted widespread attention of researchers.Due to the very large spin-orbit coupling?SOI?effect,iridium oxide of 5d electron transition group metal can be transformed into a large number of new Mott insulators by adjusting the strength of SOI relative to other interactions,which arouses people's interest in research.For ABO₃-type 5d iridium oxide SrIrO₃,the monoclinic structure is synthesized by solid-state method at ambient pressure,and it can be transformed into orthorhombic perovskite structure by high temperature and high pressure.At the same time,La-doping is introduced in A-site,or Ru-doping or Ga-doping are introduced in B-site.The effects of doping on the physical properties of materials,such as structure,magnetism and resistance,are studied and analyzed,so as to change the properties of materials and expand their investigations.In this dissertation,SrIr_1-xRu_xO₃ crystallized as orthorhombic perovskite phase was synthesized by high temperature and high pressure method.With the increase of Ru,the average bond length of Ir-O decreases,while the average bond angle of Ir-O-Ir increases.The magnetic fitting of the synthesized samples shows that when Ru is less,it is paramagnetic,while when Ru is more,the nearest Ru and Ir should be antiparallel,so they are statistically close to ferrimagnetism.In addition,the saturation magnetization M_s,coercivity H_c and residual magnetization M_r of Ru-doped samples are increasing in the overall trend.Analyzing the properties of their electrical transport,we can know that all the samples exhibit the metal to insulator transition and behave as non-Fermi-liquid in the metal phase?except x=1.0?.When Ru doping is introduced,the residual resistance ratio?RRR?increases,which indicates that the metallicity enhances,and the magnetoresistance decreases with a positive value?except x=1.0?.Sr_1-xLa_xIrO₃ with orthogonal structure was prepared by high temperature and high pressure method.With the introduction of La doping,the cell volume increases.The tolerance factor t of the synthesized samples is above 0.95,which indicates that the perovskite phase is relatively stable.With the increase of La doping content,the average bond angle of Ir-O-Ir decreases gradually,and the average bond length of Ir-O increases gradually.In the whole doping range,the samples have no magnetic order.However,they are not ordinary paramagnetic,but exchange enhanced Pauli paramagnetism.The synthesized samples are all metal phases.The magnetoresistance MR decreases with the introduction of La doping,but increases with the increase of H.Orthogonal SrIr_1-xGa_xO₃ samples were synthesized at 4 GPa and 1200?.With the increase of Ga doping concentration,the cell parameters?a,b,c?and cell volume?V?of the synthesized samples decrease,while the average bond angle of Ir-O-Ir increases.When the concentration of Ga is different,the samples are paramagnetic,and there is no magnetic order.However,they are not ordinary paramagnetism,but Pauli paramagnetism formed by enhanced exchange.After adding Ga,the transition temperature T_MII of the metal-insulator transition moves to the high temperature part.When the proportion of adding Ga is large,it is an insulator in the temperature measuring area.The resistivity of the synthesized sample increases with the increase of Ga doping amount in the temperature measurement region,but the magnetoresistance decreases with the introduction of Ga.