Development of a new superconductor on oxide single crystals by an electrostatic carrier doping

KTaO_3是一种对杂质原子具有低固溶性的氧化物半导体。因此，KTaO_3中的载流子密度被限制在1以下。4×10^<14> cm^<-2>化学掺杂。采用新的器件结构和离子液体在KTaO_3单晶（100）表面制备了双电层晶体管，其载流子密度比化学掺杂提高了一个数量级。KTaO_3在低温和45 mK以下的零电阻状态下表现出金属导电性，这表明KTaO_3具有超导性，这是利用电场效应方法开发的新型超导体的第一个例子。

KTaO_3 is an oxide semiconductor that has low solid solubility to impurity atoms. Therefore, charge carrier density in KTaO_3 has been limited below 1. 4×10^<14> cm^<-2> by chemical doping. We developed an electric double layer transistor on(100) surface of KTaO_3 single crystal by employing a new device configuration and an ionic liquid, and we induced one order of magnitude higher charge carrier density than that by chemical doping. KTaO_3 showed metallic conduction at low temperature and zero resistance state below 45 mK. This indicates superconductivity in KTaO_3, which is the first example of a new superconductor developed by the electric field-effect method.