A Superconducting Field-Effect Switch

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Abstract
We report here on a novel realization of a field-effect device that allows switching between insulating and superconducting states, which is the widest possible variation of electrical properties of a material. We chose C 60 as the active material because of its low surface state density and observed superconductivity in alkali metal–doped C 60 . We induced three electrons per C 60 molecule in the topmost molecular layer of a crystal with the field-effect device, creating a superconducting switch operating up to 11 kelvin. An insulator was thereby transformed into a superconductor. This technique offers new opportunities for the study of superconductivity as a function of carrier concentration.