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Discovery of an Artificial Two Dimensional Superconductor with Graphene-like Structure

Recently, Prof. Jian Wang at Peking University, in collaboration with Prof. Qi-Kun Xue, Prof. Xu-Cun Ma, Prof. Xin-Cheng Xie, Prof. Xi Chen, Prof. Lin Gu, Prof. Hui Yang, Prof. Mingliang Tian, and Prof. Lian Li etc discovered a new 2D superconductor with graphene or silicone-like structure formed by the substrate. It is two-atom layer crystalline Ga grown on GaN(0001) by molecular beam epitaxy (MBE). Both in situ scanning tunneling spectroscopy and ex situ electrical magnetotransport and magnetization measurements show the superconductivity in such two-atom layer crystalline Ga. The superconducting transition temperature TC is 5.4 K, which is 5 times higher than TC in stable bulk Ga phase. The graphene-like structure, which is totally different with Ga bulk structure, might also induce some interesting properties in this two dimensional material. Besides, GaN substrate is a wide used semiconductor in industry, our result demonstrates a pathway for exploring atomic-scale 2D superconductors by surface and interface engineering in a broad range of metal-semiconductor heterostructures, which benefit from present semiconductor technology and ultrathin film fabrication technique. The results were published in Physical Review Letters (PRL 114, 107003(2015)) as an Editors’ Suggestion paper. Jian Wang and Xu-Cun Ma are corresponding authors of this paper. Huimin Zhang, Yi Sun and Wei Li contributed equally to this work.

The work was supported by National Basic Research Programs of China, National Natural Science Foundation of China, the Research Fund for the Doctoral Program of Higher Education (RFDP) of China, and Collaborative Innovation Center of Quantum Matter, China.



Figure 1. Transmission electron microscopy (TEM) image of the interface of two-atom layer Ga on GaN substrate.



Figure 2. Transport result showing an onset Tc of 5.4 K. The inset is a schematic measurement structure.