School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA.
Phys Rev Lett. 2011 Jul 8;107(2):027001. doi: 10.1103/PhysRevLett.107.027001. Epub 2011 Jul 7.
The electrical transport properties of ultrathin YBa₂Cu₃O(7-x) films have been modified using an electric double layer transistor configuration employing an ionic liquid. A clear evolution from superconductor to insulator was observed in nominally 7 unit-cell-thick films. Using a finite size scaling analysis, curves of resistance versus temperature, R(T), over the temperature range from 6 to 22 K were found to collapse onto a single scaling function, which suggests the presence of a quantum critical point. However, the scaling fails at the lowest temperatures indicating the possible presence of an additional phase between the superconducting and insulating regimes.
采用离子液体的电双层晶体管结构来修饰超薄 YBa₂Cu₃O(7-x) 薄膜的电输运性质。在名义上厚度为 7 个单胞的薄膜中观察到从超导体到绝缘体的明显转变。使用有限尺寸标度分析，发现 6 至 22 K 温度范围内的电阻与温度 R(T) 曲线可以合并到单个标度函数上，这表明存在量子临界点。然而，在最低温度下，标度失效表明在超导和绝缘态之间可能存在额外的相。
