Competing strain relaxation mechanisms in epitaxially grown Pr0.48Ca0.52MnO3 on SrTiO3

We investigated the impact of strain relaxation on the current transport of Pr0.48Ca0.52MnO3(PCMO) thin films grown epitaxially on SrTiO3 single crystals by pulsed laser deposition. The incorporation of misfit dislocations and the formation of cracks are identified as competing mechanisms for the relaxation of the biaxial tensile strain. Crack formation leads to a higher crystal quality within the domains but the cracks disable the macroscopic charge transportthrough the PCMO layer. Progressive strain relaxation by the incorporation of misfit dislocations,on the other hand, results in a significant decrease of the activation energy for polaron hoppingwith increasing film thickness.