Interfaces of Ag/SrTiO3/La0.67Ca0.33MnO3 structures studied by the temperature and magnetic-field responses of their capacitance -: art. no. 184433

The temperature dependence of the dielectric permittivity, epsilon, of a (600 nm)SrTiO3 layer in a Ag/SrTiO3/La0.67Ca0.33MnO3 heterostructure was determined from room temperature down to helium temperature. It follows a (T-T-CW)(-1) relation at 80-220 K, witnessing a high quality of the dielectric film. It is possible to study interface contributions to the capacitance and to estimate the characteristic length of electric field penetration into the La0.67Ca0.33MnO3 film. A relatively long length of about 1.2 nm at T<220 K indicates a depletion of charge at the interface and/or a contribution from a phase separation in the manganite. The effective capacitance of the heterostructure increased about 7%-8% if a magnetic field of 0.4 T was applied at the phase transition point, T-Curie, of the manganite electrode.