Possible ferromagnetism induced in otherwise nonmagnetic materials has been motivating intense research in complex oxide heterostructures. Here we show that a confined magnetism is realized at the interface between SrTiO3 and two insulating polar oxides, BiMnO3 and LaAlO3. By using polarization dependent x-ray absorption spectroscopy, we find that in both cases the magnetism can be stabilized by a negative exchange interaction between the electrons transferred to the interface and local magnetic moments. These local magnetic moments are associated with magnetic Ti3+ ions at the interface itself for LaAlO3/SrTiO3 and to Mn3+ ions in the overlayer for BiMnO3/SrTiO3. In LaAlO3/SrTiO3 the induced magnetism is quenched by annealing in oxygen, suggesting a decisive role of oxygen vacancies in this phenomenon.

Nanopores, either biological, solid-state, or ultrathin pierced graphene, are powerful tools which are central to many applications, from sensing of biological molecules to desalination and fabrication of ion selective membranes. However, the interpretation of transport through low aspect-ratio nanopores becomes particularly complex as 3D access effects outside the pores are expected to play a dominant role. Here, we report both experiments and theory showing that, in contrast to naïve expectations, long-range mutual interaction across an array of nanopores leads to a non-extensive, sub-linear scaling of the global conductance on the number of pores N. A scaling analysis demonstrates that the N-dependence of the conductance depends on the topology of the network. It scales like G ∼ N/log N for a 1D line of pores, and like G ∼ √ N for a 2D array, in agreement with experimental measurements. Our results can be extended to alternative transport phenomena obeying Laplace equations, such as diffusive, thermal, or hydrodynamic transport. Consequences of this counter-intuitive behavior are discussed in the context of transport across thin membranes, with applications in energy harvesting.

We combine transport experiments, advanced ab initio calculations, and model analysis to determine the thermoelectric power in the two-dimensional electron gas formed at the paradigmatic oxide interface SrTiO3/LaAlO3. We demonstrate that contrary to popular expectation, quantum confinement does not enhance the thermoelectric power of the electron gas at this interface with respect to its corresponding three-dimensional case. Our analysis directly relates the thermopower behavior to band structure characteristics typical of the oxide heterostructure (i.e., on-site and intersite band splitting), furnishing general interpretive prescriptions to search for oxide heterostructures with improved thermoelectric capabilities

The transport characterization in the dark and under light irradiation of three different interfaces-LaAlO3/SrTiO3, LaGaO3/SrTiO3, and the novel NdGaO3/ SrTiO3 heterostructure is reported. All of them share a perovskite structure, an insulating nature of the single building blocks, a polar/non-polar character, and a critical thickness of four unit cells for the onset of conductivity. The interface structure and charge confinement in NdGaO3/SrTiO3 are probed by atomic-scale-resolved electron energy loss spectroscopy showing that, similarly to LaAlO3/SrTiO3, extra electronic charge confined in a sheet of about 1.5 nm in thickness is present at the NdGaO3/SrTiO3 interface. Electric transport measurements performed in the dark and under radiation show remarkable similarities and provide evidence that the persistent perturbation induced by light is an intrinsic peculiar property of the three investigated oxide-based polar/non-polar interfaces. This sets a framework for understanding the previous contrasting results found in the literature about photoconductivity in LaAlO3/SrTiO3 and highlights the connection between the origin of persistent photoconductivity and the origin of conductivity itself. An improved understanding of the photoinduced metastable electron-hole pairs might allow light to be shed directly on the complex physics of this system and on the recently proposed perspectives of oxide interfaces for solar energy conversion