Steady strong magnetic field device helps discover ultra-high conductivity materials
A research team led by Xiu Faxian, a professor of the Department of Physics of Fudan University, who is a user of the steady-state strong magnetic field experimental device (SHMFF), observed that its surface state has ultra-high conductivity in the niobium arsenide nanoribbon, which is also the current two-dimensional non-superconducting system The highest electrical conductivity, the mechanism of its low electron scattering probability comes from the Fermi arc structure unique to Weir semimetal. On March 18th, the related research paper "Ultrahigh conductivity in Weyl semimetal NbAs nanobelts" was published online in "Nature Materials" in long form .
Materials can be classified according to electrical conductivity: if electrons are not allowed to flow in the material, it is called an insulator; if there are a large number of free electrons in the material that can participate in conduction, it is called a conductor. In order to solve the problem of device heat dissipation, people have been looking for some materials with ultra-high conductivity. Generally speaking, there are two ways to increase conductivity. The first is to increase the number of electrons, and the second is to make the electrons run faster. But in traditional materials, these two are difficult to achieve at the same time. This is mainly due to the fact that when the number of electrons is large, the electrons will greatly increase the probability of scattering due to the increase of the Fermi surface. Some of these large-angle backscattering will make the movement of electrons diverge, thereby reducing the mobility and limiting the material conductivity. Sex is further enhanced.
Recently, Xiu Faxian's research group successfully synthesized niobium arsenide nanoribbons. The measurement found that the niobium arsenide nanoribbons still have ultra-high mobility even with a high electron concentration. In order to further confirm what caused the ultra-high conductivity of the niobium arsenide nanoribbons, Zhang Jinglei, associate researcher of the Strong Magnetic Field Science Center of the Hefei Institute of Material Science, Chinese Academy of Sciences and others used a steady-state strong magnetic field experimental device to systematically study arsenization Quantum oscillation of niobium nanoribbons. Thanks to the higher test magnetic field (the highest field used is 32T), the research team observed a series of quantum oscillations composed of Fermi arc surface states. Through the analysis of these quantum oscillations, the researchers found that the surface state of the Fermi arc in niobium arsenide has the characteristics of low scattering rate. Even at a higher electron concentration, the system still maintains a low probability of scattering. These experimental results prove that the mechanism of ultra-high conductivity of niobium arsenide is derived from the Fermi arc structure unique to Weir semimetal. It is worth noting that, unlike conventional quantum phenomena, the characteristic of Fermi arcs is still effective even at room temperature.
This discovery provides a feasible idea for materials science to find high-performance conductors. With this special electronic structure, it is possible to increase the number of electrons while reducing electron scattering, thereby achieving excellent electrical conductivity, which has potential applications in reducing energy consumption of electronic devices.
The research work was carried out in cooperation with Fudan University, the Chinese Academy of Sciences Strong Magnetic Field Science Center, Nanjing University, University of California Davis, Queensland University, Beijing University of Technology, Zurich Federal Institute of Technology, Trinity College of Ireland and other units. Xiu Faxian is the corresponding author. Fudan University doctoral student Zhang became the first author. Fudan University undergraduate student Ni Zhuoliang, strong magnetic field center Zhang Jinglei and Fudan University doctoral student Yuan Xiang are co-first authors.
The research in the strong magnetic field center's experimental part was supported by the scientific research equipment research project of the Chinese Academy of Sciences, the Youth Promotion Association of the Chinese Academy of Sciences, and the innovation project cultivation fund of the Hefei Material Science and Technology Center.
Left: Quantum oscillation of niobium arsenide nanoribbons under high magnetic field; right: Comparison of conductivity of niobium arsenide nanoribbons with other two-dimensional materials.
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