Nanoscale Control of the Metal-Insulator Transition at LaAlO3/KTaO3 Interfaces

Recent reports of superconductivity at KTaO3 (KTO) (110) and (111) interfaces have sparked intense interest due to the relatively high critical temperature as well as other properties that distinguish this system from the more extensively studied SrTiO3 (STO)-based heterostructures. Here, we report the reconfigurable creation of conducting structures at intrinsically insulating LaAlO3/ KTO(110) and (111) interfaces. Devices are created using two distinct methods previously developed for STO-based heterostruc-tures: (1) conductive atomic-force microscopy lithography and (2) ultralow-voltage electron-beam lithography. At low temperatures, KTO(110)-based devices show superconductivity that is tunable by an applied back gate. A one-dimensional nanowire device shows single-electron-transistor (SET) behavior. A KTO(111)-based device is metallic but does not become superconducting. These reconfigurable methods of creating nanoscale devices in KTO-based heterostructures offer new avenues for investigating mechanisms of superconductivity as well as development of quantum devices that incorporate strong spin-orbit interactions, superconducting behavior, and nanoscale dimensions.

Automated summary

Recent reports of superconductivity at KTaO3 (KTO) (110) and (111) interfaces have generated significant interest due to the higher critical temperature and unique properties compared to the more extensively studied SrTiO3 (STO)-based heterostructures. In this study, researchers have successfully created reconfigurable conducting structures at intrinsically insulating LaAlO3/ KTO(110) and (111) interfaces using two established methods. The KTO(110)-based devices exhibit tunable superconductivity at low temperatures, while a one-dimensional nanowire device demonstrates single-electron-transistor behavior. However, the KTO(111)-based device remains metallic without becoming superconducting. These findings present new opportunities for investigating superconductivity mechanisms and developing quantum devices with strong spin-orbit interactions, superconducting behavior, and nanoscale dimensions.