Colossal elastoresistance of phase separated (Pr1-yLay)0.7Ca0.3MnO3 thin films

The use of a piezoelectric substrate, PMN-PT(001)(PbMg1/3Nb/3O3)0.72(PbTiO3)0.28, allows us to biaxially compress as grown epitaxial films by as much as 0.2%. This reversible dynamic strain process gives a unique insight into the effect of strain on perovskite oxides, eliminating effects such as varying oxygen concentration, which may occur when several substrates with different lattice mismatch are used. We have prepared phase separated PLCMO (Pr1-yLay)0.7Ca0.3MnO3 films on PMN-PT for a range of y values. Around y=0.6, the system exhibits a transition from an insulating to a metallic ground state. When partially releasing the as grown tensile strain of the PLCMO film by piezo-compression of the substrate, we find a huge reduction of the resistance, or colossal elastoresistance. The relaxed films show an enhanced magnetisation and an increase in magnetic transition temperature. Thus we can conclude that tensile strain efficiently suppresses the ferromagnetic conducting phase and favours the charge ordered state.