Unusual Quantum Oscillations and Indications of Non-Trivial Electronic States in a Quassi Two-Dimentional Electron System at Intricate Oxide Interfaces

Two-dimensional electron systems (2DES) built from perovskite transition metal oxides are potential prospects for the next generation of spintronics and quantum computing due to the simultaneous occurrence of electric-field driven superconductivity and spin-orbit interaction. To enhance technological applications, it is necessary to fully comprehend the electronic bands and confirm the anticipated electronic states in these 2DES by experimentation. Here, using thorough studies of Shubnikov-de Haas oscillations in two distinct systems, EuO/KTaO₃ (EuO/KTO) and LaAlO₃/SrTiO₃ (LAO/STO), we give new insights into the electronic states of the 2DES at oxide interfaces. We performed transport tests in high magnetic fields up to 60 T and low temperatures down to 100 mK in order to precisely resolve these oscillations. We saw a progressive increase in oscillations for 2D confined electrons at both contacts. We saw a progressive increase in oscillation frequency and cyclotron mass with the magnetic field for 2D confined electrons at both interfaces. We analyze these fascinating results by taking into account the possibility of non-trivial electronic bands, for which both linear and parabolic dispersion relations are included in the E−k dispersion. The unconventional oscillations presented in this study not only establish a new paradigm for quantum oscillations in 2DES based on perovskite transition metal oxides, where the oscillations frequency exhibits quadratic dependence on the magnetic field, but also provide experimental evidence for topological-like electronic states in KTO-2DES and STO-2DES.