Our group observed that the surface state of niobium arsenide nanoribbons has ultrahigh conductivity, which is currently the highest conductivity in the two-dimensional system. The mechanism of its low electron scattering probability originates from the unique electronic structure of the Weyl semimetal (i.e. the Fermi arc surface state). On March 18th, the relevant research findings were published online in Nature Materials (DOI: 10.1038/s41563-019-0320-9) under the title Ultrahigh conductivity in Weyl semimetal NbAs nanobelts. Professor Faxian Xiu is the corresponding author, and doctoral student Cheng Zhang of our group is the first author. Undergraduate student Zhuoliang Ni from the Department of Physics at Fudan University, associate researcher Jinglei Zhang from the High Magnetic Field Laboratory of the Chinese Academy of Sciences, and doctoral student Xiang Yuan of our group are the co first authors.
Conductors are one of the indispensable materials in the manufacturing of integrated circuits, widely used for interconnecting components and forming inductive components. As the feature size of integrated circuits becomes smaller, the integration level becomes higher, and the interconnections between devices become denser, the heat generated by the current flowing through these fine conductors becomes more and more significant, which to some extent restricts the further development of chips. Therefore, searching for ultra-high conductivity materials has become an important research goal for people.
Our group has discovered nearly perfect conductive properties in the special material of Weyl semimetal, providing a new idea for searching for ultrahigh conductive materials. There are two ways to increase conductivity. One is to increase the number of electrons, and the other is to make them run faster. But it is difficult to achieve both at the same time. In the case of a large number of electrons, there will be a lot of scattering, and some of the scattering is at a large angle, which leads to the movement of electrons going in opposite directions. we found in the semimetal NbAs that although the internal conductivity of the material is relatively ordinary, there is an abnormally good conductivity channel on its surface. And it is precisely due to the special electronic structure of the Fermi arc on the surface of the Weyl semimetal that even with many electrons, there will be no large angle scattering, ensuring that all electrons move in one direction. This greatly improves the efficiency of electronic transmission. Therefore, based on this new conductivity mechanism, our group has achieved the best conductivity in the current two-dimensional system, which is 1000 times higher than graphene.
In the field of topological semimetals and outer semimetals, our group has always insisted on doing basic and original work. In this achievement, for the first time, NbAs nanobelts were successfully prepared through the chemical reaction of niobium chloride, arsenic, and hydrogen gas, becoming the world's first research group to achieve wail semi metallic nanostructures. Faxian Xiu stated that the discovery of this nanomaterial and the proposal of new conductive materials provide a feasible approach for finding higher performance conductive materials. It can increase the number of electrons in a conductor while reducing electron scattering, thereby achieving excellent conductivity characteristics. It has potential application value in power transmission and low-power devices.
Paper link: https://www.nature.com/articles/s41563-019-0320-9
