Colossal piezoresistance in phaseseparated manganites

We have measured the strain dependent transport properties of phase separated manganite thin films. We subjected (La_1-yPr _y)_1-xCa_xMnO₃ thin films grown on NdGaO₃(110) substrates to direct external mechanical stress using a three-point beam bending method. The resultant change in resistance reveals a colossal piezoresistance (CPR) in manganites. Our experiments reveal that phase separation is a necessary but not sufficient condition for CPR. The maximum CPR is observed only when the phase boundaries are free to move in the fluid-like phase separated state. Our results show that both long-range strain interactions and quenched disorder play an important role in micrometer scale phase separation in manganites, albeit in different temperature ranges.