Recently, perovskite related BaPbO3 has attracted attention due to its hidden topological properties and, moreover, has been used as a thin layer in heterostructures to induce two-dimensional superconductivity. Here we investigate the normal state electronic transport properties of thin films of BaPbO3. Temperature and magnetic field dependent sheet resistances are strongly affected by two-dimensional quantum effects. Our analysis decodes the interplay of spin-orbit coupling, disorder, and electron-electron interaction in this compound. Similar to recently discussed topological materials, we find that weak antilocalization is the dominant protagonist in magnetotransport, whereas electron-electron interactions play a pronounced role in the temperature dependence. A systematic understanding of these quantum effects is essential to allow for an accurate control of properties not only of thin films of BaPbO3, but also of topological heterostructures.

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Oxide heterostructures allow for detailed studies of 2D electronic transport phenomena. Herein, different facets of magnetotransport in selected spin–orbit‐coupled systems are analyzed and characterized by their single‐band and multiband behavior, respectively. Experimentally, temperature and magnetic field dependent measurements in the single‐band system BaPbO3/SrTiO3 reveal strong interplay of weak antilocalization (WAL) and electron–electron interaction (EEI). Within a scheme which treats both, WAL and EEI, on an equal footing a strong contribution of EEI at low temperatures is found which suggests the emergence of a strongly correlated ground state. Furthermore, now considering multiband effects as they appear, e.g., in the model system LaAlO3/SrTiO3, theoretical investigations predict a huge impact of filling on the topological Hall effect in systems with intermingled bands. Already weak band coupling produces striking deviations from the well‐known Hall conductivity that are explainable in a fully quantum mechanical treatment which builds upon the hybridization of intersecting Hofstadter bands.

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