Current-Induced Reversible Resistance Jumps in La_0.8Ca_0.2MnO_3 Microbridge

Two spatially confined La_0.8Ca_0.2MnO_3 (LCMO) microbridges with different widths, starting from a single LCMO film (3 mm\times5 mm), are fabricated by optical lithography. A second new and robust metal-insulator transition (MIT) peak at about 75 K appears, in addition to the normal MIT at 180 K observed in the standard LCMO film. When the two bridges are processed by currents of high densities, interesting reversible resistance jumps are excited only around the new peak. A stronger dependence of resistance jump on current excitation is found for the bridge with a smaller width. The temperature driven transition between new excited multiple metastable states are involved to explain the interesting low-temperature ultra-sharp jumps.