Surface Charge Writing and Nonvolatile Control of Superconductivity in a LaAlO3/KTaO3(111) Heterostructure

The oxide interface between LaAlO3 and KTaO3(111) can host an electron gas that condenses into superconductivity at low temperatures. In this work, we demonstrate a local and nonvolatile control of this electron gas using a biased conducting atomic force microscope tip. By scanning the tip, charges can be accumulated on the surface of LaAlO3, which subsequently tune the conduction of the buried LaAlO3/KTaO3(111) interface largely, varying from conducting (superconducting) to insulating states. The tuning effects are stable for >20 h at room temperature. The maximum modulation of carrier density is >8 ?? 1013/cm2. This result suggests a model system in which rewritable superconducting, normal, and insulating states can be flexibly defined in the same material on demand.