Electromagnetic Properties Of Sr-doped LaMnO₃Superlattice

The perovskite oxide systems of LaMnO₃（LMO） have been condensed matter physicsresearch is one of the hot issues in recent years because of the special structure andmagnetoelectric characteristics of the singular nature. This kind of material has been widelyused in the solid fuel cells, solid electrolyte, sensors and catalysis. Before and after1990, withthe giant magnetoresistance effect of discovery, this kind of oxide has caused people moreinterestings. Pure LMO is orthogonal crystal structure under room temperature, researchshows that LMO electronic conductivity can increase through doping low-cost metal insteadof La or Mn position, and because SrMnO₃（SMO） doped LMO material has the very highelectromagnetic resistance, and long-term chemical stability, so it is very goodelectromagnetic material.Recently, with the methods of atomic layer extension preparated LMO/SMO superlatticewhich caused people more and more interests and concerns. They are very sensitive toexternal conditions, such as doping, electric field, magnetic field, temperature, strain, etc.Particularly, strain plays a very important role in structure and electrical properties ofLa_1-xSr_xMnO₃（LSMO）. Previous research shows that different strain will induce magneticorderly shift of LSMO. In order to convenient research, Cao adopted simple cubic model ofLSMO, find with the c axis strain, LSMO of ferromagnetic will change to antiferromagnetic,at the same time, the pzof in the px、py、pzwhich are the O atom2p orbit Components almostto zero. But both at home and abroad, has few electromagnetic properties reports about theorthogonal structure of La/SrMnO₃in a axis, b axis and ac axis of strain. In fact, orthogonalstructure is the eigenvalue structure which under normal temperature.Based on the first principle of density functional theory, this paper studied the latticeconstant, axial strains, and electrical magnetic structure of orthogonal superlatticeLaMnO₃/SrMnO₃（LMO/SMO）. Theoretical calculation results show that LMO/SMO isenergically favorable to be ferromagnetic other than anti-ferromagnetic with axial strainsalong the a, b, c, and ac directions. Upon Sr-doping, the orthogonal structure of LMO stillremains obvious lattice distortion, and the face-centered cubic SMO is introduced latticedistortion into it. The3d state of Mn and2p state of O are more complex with different axialstrains. Ferromagnetic property of LMO/SMO is mainly introduced by the difference of3dstate of Mn majority and minority, which are tend to be symmetrical with increasing negativeaxial strains. At the same time, magnetic property tends to be zero. And on this basis, we havecalculated the bandstructure and density of states, provide the theoretical support forexperimental research and practical application...