Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA.
Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot, Israel.
Nat Nanotechnol. 2023 Apr;18(4):331-335. doi: 10.1038/s41565-022-01314-x. Epub 2023 Jan 30.
Electrical control of superconductivity is critical for nanoscale superconducting circuits including cryogenic memory elements, superconducting field-effect transistors (FETs) and gate-tunable qubits. Superconducting FETs operate through continuous tuning of carrier density, but no bistable superconducting FET, which could serve as a new type of cryogenic memory element, has been reported. Recently, gate hysteresis and resultant bistability in Bernal-stacked bilayer graphene aligned to its insulating hexagonal boron nitride gate dielectrics were discovered. Here we report the observation of this same hysteresis in magic-angle twisted bilayer graphene (MATBG) with aligned boron nitride layers. This bistable behaviour coexists alongside the strongly correlated electron system of MATBG without disrupting its correlated insulator or superconducting states. This all-van der Waals platform enables configurable switching between different electronic states of this rich system. To illustrate this new approach, we demonstrate reproducible bistable switching between the superconducting, metallic and correlated insulator states of MATBG using gate voltage or electric displacement field. These experiments unlock the potential to broadly incorporate this new switchable moiré superconductor into highly tunable superconducting electronics.
超导的电控对于包括低温存储元件、超导场效应晶体管（FET）和栅可调谐量子比特在内的纳米级超导电路至关重要。超导 FET 通过连续调整载流子密度来工作，但尚未报道具有双稳态的超导 FET，它可以作为一种新型的低温存储元件。最近，在与绝缘六方氮化硼栅介质对准的 Bernal 堆叠双层石墨烯中发现了栅极滞后和由此产生的双稳性。在这里，我们报告了在具有对准的氮化硼层的魔角扭曲双层石墨烯（MATBG）中观察到相同滞后的情况。这种双稳行为与 MATBG 的强关联电子系统共存，而不会破坏其关联绝缘或超导状态。这个全范德华平台使我们能够在这个丰富系统的不同电子状态之间进行可配置的切换。为了说明这种新方法，我们使用栅极电压或电位移场演示了 MATBG 的超导、金属和关联绝缘状态之间可重复的双稳切换。这些实验为广泛采用这种新型可切换的莫尔超导体进入高度可调谐的超导电子学开辟了可能性。
