Open Lecture at the Irvin/Levy Group Meeting: Giulia Meucci (Department of Energy Conversion and Storage, Technical University of Denmark)

Electronic Transport in Freestanding LaAlO3/SrTiO3 Micro-membranes Interfaces between complex oxides enable a wide range of correlated-electron phenomena. A notable example is the two-dimensional electron gas (2DEG) at the LaAlO₃/SrTiO₃ (LAO/STO) interface, which hosts strong spin–orbit coupling, magnetism, gate-controlled superconductivity, and unconventional electron pairing, that in quantum dot gives rise to a negative effective charging energy U. Freestanding LAO/STO micro-membranes extend this platform into a flexible, easily integrable, and highly tunable geometry for transport studies. In this presentation, I will discuss electronic devices based on freestanding LAO/STO membranes and show that they can naturally host negative-U centers, where lateral confinement arises intrinsically rather than from engineered nanostructures. These centers coexist with gate-tunable superconductivity and remain stable under repeated thermal cycling from millikelvin to room temperature. These results suggest that negative-U centers may arise from the intrinsic interfacial inhomogeneity typical of LAO/STO and should therefore be considered a general feature of the LAO/STO interface. Building on this, I will present preliminary results on next-generation devices incorporating local gates, to enable enhanced control over the interfacial electron density. Together, these results establish freestanding LAO/STO micro-membranes as a platform for oxide-based gate architectures and correlated-electron studies, highlighting their potential for future quantum and nanoelectronic devices.