Effect of the capping on the local Mn oxidation state in buried (001) and (110) SrTiO3/La2/3Ca1/3MnO3 interfaces

The electronic stability of (001) and (110) surfaces of La2/3Ca1/3MnO3 (LCMO) capped with nanometric SrTiO3 (STO) layers in epitaxial heterostructures is addressed by (S)TEM electron energy loss spectroscopy. It is found that growth of STO on (001)LCMO promotes a significant electron doping of LCMO that extends a few nanometers deep into the film. In contrast, (110)LCMO appears to be electronically more robust and no electronic reordering has been observed. These results are in clear correlation with the distinct magnetic properties observed in those interfaces and illustrate that complex chemical phenomena take place at interfaces among multivalent oxides.