1] Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794-3800, USA [2].
Nat Commun. 2013;4:2716. doi: 10.1038/ncomms3716.
The interplay of the massless Dirac fermions in graphene and the Cooper pair states in a superconductor has the potential to give rise to exotic physical phenomena and useful device applications. But to date, the junctions formed between graphene and superconductors on conventional substrates have been highly disordered. Charge scattering and potential fluctuations caused by such disorder are believed to have prevented the emergence or observation of new physics. Here we propose to address this problem by forming suspended graphene-superconductor junctions. We demonstrate the fabrication of high-quality suspended monolayer graphene-NbN Josephson junctions with device mobility in excess of 150,000 cm(2) per Vs, minimum carrier density below 10(10) cm(-2), and the flow of a supercurrent at critical temperatures greater than 2 K. The characteristics of our Josephson junctions are consistent with ballistic transport, with a linear dependence on the Fermi energy that reflects of linear dispersion of massless Dirac fermions.
在无质量狄拉克费米子的相互作用和超导体中的库珀对态有可能产生奇异的物理现象和有用的器件应用。但是迄今为止，在传统衬底上形成的石墨烯和超导体之间的结具有高度的无序性。由于这种无序性引起的电荷散射和电势波动被认为阻止了新物理的出现或观察。在这里，我们提出通过形成悬浮石墨烯-超导体结来解决这个问题。我们展示了高质量悬浮单层石墨烯-NbN 约瑟夫森结的制造，其器件迁移率超过 150000cm²/Vs，载流子密度低于 10¹⁰cm⁻²，在大于 2 K 的临界温度下流动超导电流。我们的约瑟夫森结的特性与弹道传输一致，费米能呈线性关系，这反映了无质量狄拉克费米子的线性色散。
