Center for Supersolid &Quantum Matter Research and Department of Physics, KAIST, Daejeon, 305-701, Republic of Korea.
Sci Rep. 2017 Feb 20;7:42969. doi: 10.1038/srep42969.
The superconductor-insulator (SI) transition in two-dimensional Ta thin films is investigated by controlling both film thickness and magnetic field. An intriguing metallic phase appears between a superconducting and an insulating phase within a range of film thickness and magnetic field. The temperature and electric field scaling analyses are performed to investigate the nature of the SI transition in the thickness-tuned metallic and superconducting samples. The critical exponents product of νz obtained from the temperature scaling analysis is found to be approximately 0.67 in the entire range of film thickness. On the other hand, an apparent discrepancy is measured in the product of ν(z + 1) by the electric filed analysis. The product values are found to be about 1.37 for the superconducting films and about 1.86 for the metallic films respectively. We find that the discrepancy is the direct consequence of electron heating that introduces additional dissipation channels in the metallic Ta films.
二维 Ta 薄膜中超导-绝缘（SI）转变通过控制薄膜厚度和磁场来研究。在一定的薄膜厚度和磁场范围内，在超导相和绝缘相之间出现了一个有趣的金属相。通过温度和电场标度分析来研究厚度调谐的金属和超导样品中 SI 转变的性质。从温度标度分析中得到的 νz 的临界指数乘积在整个薄膜厚度范围内约为 0.67。另一方面，通过电场分析测量到 ν(z + 1)的乘积存在明显差异。超导薄膜的乘积值约为 1.37，金属薄膜的乘积值约为 1.86。我们发现，这种差异是电子加热的直接结果，电子加热在金属 Ta 薄膜中引入了额外的耗散通道。
