Device size dependence of resistance switching performance in metal/manganite/metal trilayers

We have fabricated epitaxial Pr0.8Ca0.2MnO3 (PCMO) insulator layers sandwiched between Al top electrodes and epitaxial La0.6Sr0.4MnO3 bottom electrode layers on (LaAlO3)0.3-(Sr2AlTaO6)0.7 (1 0 0) substrates. Various sizes of metal/insulator/metal device structures were formed by photolithography and Ar ion milling. Device size dependence of Al/PCMO interface resistances was well fitted by series-parallel equivalent circuit, indicating several types of different resistance components exist at the Al/PCMO interfaces. These different resistance components suggest that defects might distribute inhomogeneously at the Al/PCMO interfaces which exhibit the resistance switching.