Abstract
Manganites fueled the interests of the research community by the discovery of colossal magnetoresistance (CMR) effect in the 1990s. The unexpected sensitivity of resistance to applied magnetic fields is as high as 10^5%, which offered a new challenge to the condensed matter theories and showed great potential in application. The properties of ZnO are of great interest because of its wide direct band gap. Due to the various intriguing and perplexing properties zinc oxides and manganites exhibit, several work have been done on studying the heterostructures composed with manganites and ZnO. Excellent rectifying behaviors have been observed by several groups. A positive magnetoresistance as high as 54% at H=0.5T are also reported.
In this work, the p-n junctions, consisting of p-type Pr0.7Sr0.3MnO3 (PSMO) and n-type ZnO layers, have been fabricated on Al2O3 (012) substrates by using pulsed laser deposition. The x-ray diffraction pattern of PSMO/ZnO/sapphire heterostructure implies high degree of epitaxy and good crystallinity. Such junctions also exhibited reproducible rectifying behaviors over a large temperature range. It is expected that the junction properties can be modified by applying different magnetic fields. The influences of optical and strain fields on the junction behaviors will also be investigated.