Evolution of percolating behavior in La0.325Pr0.3Ca0.375MnO3 micro/nanowires

La5/8-xPrxCa3/8MnO3 (LPCMO) is a prototypical electronic phase separation material whose scaling property and size dependence have attracted much attention due to its potential applications in electronic devices. In this study, planar-structured single LPCMO micro/nanowire devices with diameters ranging from 100 nm to several microns were fabricated using an electro-spinning method. We found that the metal-insulator transition of the LPCMO wire was suppressed and finally disappeared with decreasing diameter. We suggest that such transport behavior originates from the size limitation of the percolating characteristic. Several ferromagnetic percolating paths formed in the micron-sized device, evidenced by step-like jumps in the magnetoresistance measurements. For the submicrometer-sized devices, the percolating behavior was severely decreased, resulting in a significant reduction of magnetic response by more than three orders of magnitude. These results indicate that the scaling limitation of the percolating characteristic plays a key role in performance modulation of phase separation material based nano-devices, and should be carefully considered in device design.