Significant discovery of graphene superconductivity, research from Shanghai Jiao Tong University published in Nature

On June 20, it was learned from the official WeChat account of Shanghai Jiao Tong University that the research team of Shanghai Jiao Tong University observed superconductivity in single-crystal graphene under electron doping for the first time, and the relevant results were published in Nature.

Superconductivity, a macroscopic quantum phenomenon, was first observed by Dutch scientist HK Onnes in 1911 while studying the electrical transport properties of mercury at low temperatures. It is one of the milestone discoveries in condensed matter physics.

This research by Shanghai Jiao Tong University is of great significance for understanding the superconducting mechanism of crystalline graphene and twisted graphene systems, and for designing and preparing high-quality new superconducting quantum devices based on graphene systems.

The experimental team successfully prepared high-quality double-layer graphene and tungsten diselenide heterojunction samples, making it possible to apply a vertical displacement electric field of up to 1.6 V/nm.

▲ Schematic diagram of sample structure and optical microscope photo

By conducting systematic ultra-low temperature quantum transport measurements and combining electric field regulation with electrostatic doping regulation, the experimental team revealed the complete phase diagram of hole-doped superconductivity in this system as the displacement electric field and carrier concentration change.

The experimental team observed a superconducting state under electron doping conditions, which is the first time that electron doped superconductivity has been observed in single-crystal graphene.

▲ The phase diagram of the double-layer graphene and tungsten diselenide heterojunction system revealed by the experiment, and the superconducting state of the hole and electron doping observed

The superconducting state intensity at both the hole end and the electron end can be effectively adjusted by an external vertical displacement electric field. The highest superconducting transition temperatures measured experimentally are approximately 450 mK and 300 mK, respectively, which are also the highest records of superconducting transition temperatures observed in single-crystal graphene systems.