Curious magnetism and I-V characteristics of p-n junction, switching and hysteresis of LBMO/ZnO heterostructures

Peculiar electrical and magnetic properties of La(Ba)MnO₃ thin films were obtained. These are useful for novel p-n junctions which can be unusually modulated by magnetic field. Temperature dependences of resistance and SQUID-magnetization indicate that the films have well separated insulating to metallic (T_p) and paramagnetic to ferromagnetic (T_c) transition temperatures. This can be understood by double exchange coupling (DEC) and phase separation models. The film shows negative magnetoresistance (MR) caused by DEC model, and positive MR interpreted by a magnetostriction model. Hetero-junctions of La(Ba)MnO₃/ZnO on various substrates show variety of rectifying I-V characteristics with large rectification factor. Further they show large switching and hysteretic behaviors due to metallic-phase percolation model. These behaviors are greatly modulated by light illuminations. (author)