Enhancing the charge ordering temperature in thin films of Pr0.5Ca0.5MnO3 by strain

We report the effects of biaxial strain on the charge ordering temperature Tco of the mixed-valent manganite perovskite oxide Pr0.5Ca0.5MnO3. Thin films were grown on SrTiO3, which has a 1.3% larger in-plane lattice parameter. Other substrates were used for comparison. Transport measurements combined with data from electron microscopy show that Tco is considerably enhanced. At thicknesses of the order of 10?nm, where the films are fully strained, Tco is above 320?K, more than 70?K above the bulk value of 250?K, while around 50?nm, where relaxation has set in, the enhancement is around 40?K. The bulk value is only reached at a thickness of about 150?nm.