Ferromagnetism is usually considered to be incompatible with conventional superconductivity, as it destroys the singlet correlations responsible for the pairing interaction. Superconductivity and ferromagnetism are known to coexist in only a few bulk rare-earth materials. Here we report evidence for their coexistence in a two-dimensional system: the interface between two bulk insulators, LaAlO(3) (LAO) and SrTiO(3) (STO), a system that has been studied intensively recently. Magnetoresistance, Hall, and electric-field dependence measurements suggest that there are two distinct bands of charge carriers that contribute to the interface conductivity. The sensitivity of properties of the interface to an electric field makes this a fascinating system for the study of the interplay between superconductivity and magnetism.

Using a set of scanning probe microscopy techniques, we demonstrate the reproducible tunneling electroresistance effect on nanometer-thick epitaxial BaTiO(3) single-crystalline thin films on SrRuO(3) bottom electrodes. Correlation between ferroelectric and electronic transport properties is established by direct nanoscale visualization and control of polarization and tunneling current. The obtained results show a change in resistance by about 2 orders of magnitude upon polarization reversal on a lateral scale of 20 nm at room temperature. These results are promising for employing ferroelectric tunnel junctions in nonvolatile memory and logic devices.