Creating, Engineering, and Probing 2D Electronic States in Complex Oxides

2D electronic states have enabled fundamental discoveries, including the quantum Hall effect, and exhibit a wide range of applications in microelectronics and quantum information systems. The path to 2D electronic transport, however, has remained limited to interfaces of dissimilar materials grown by highly sophisticated techniques or physical dimensional reduction, which is only possible in a handful of materials systems such as van der Waals materials. Here we study the synthesis of cubic perovskite KTaO₃ and fractionally occupied double perovskite EuTa₂O₆ via molecular-beam epitaxy, and the control of their 2D electronic states via epitaxial effects such as strain. We also discuss the 2D superconductivity of KTaO₃ interfaces and their response to an applied magnetic field in novel superconducting devices, including superconducting field effect transistors.