'Topological semi-metal' is a new class of topological electronic states different from 'topological insulators', with singular magnetic transport properties (such as chiral negative reluctance, giant magnetoresistance), and extremely high carrier mobility. It is currently a hotspot and frontier in the field of quantum materials. According to the structural characteristics of the energy band, topological semimetals can be divided into topological Dirac semi-metals, foreign semi-metals and 'Node-Line' semi-metals. In the top-of-section half-metal, the intersection of the energy bands forms a continuous closed curve in the lattice momentum space. Introducing an electron correlation effect or superconducting pairing in this flat band will hopefully achieve a fractional topological state or High transition temperature superconductivity and other new states.
Tian Mingliang researcher Ning Wei, Ph.D. student An Linlin, Zhang Hongwei, etc., using the steady-state field of water-cooled magnet 33T to study the quantum transport properties of the layered compound Nb3SiTe6 under strong magnetic field. Theoretical calculations suggest that this compound may be A new section of semi-metal. The researchers obtained different thicknesses of Nb3SiTe6 nanosheets by cleaving Nb3SiTe6 single crystals, and carefully measured the magnetoresistance behavior and Hall resistance of the nanosheets. Studies have shown that the Nb3SiTe6 nanosheets are lost. The transport process is mainly cavity-dominated, and its mobility decreases as the nanosheets become thinner. Magnetoresistance measurements show that Nb3SiTe6 nanosheets exhibit linear magnetoresistance at higher magnetic fields and are not saturated at magnetic fields up to 33T. At the same time, quantum oscillatory behavior occurs at high field (>20T). The quantum oscillations at different magnetic field angles show that the Fermi surface of Nb3SiTe6 has two-dimensional characteristics, and the electrons in the sample have a non-trivial Berry phase ( Berry phase). These experimental results give the first experimental evidence that Nb3SiTe6 is a topologically protected semi-metallic material.
The research was published in the journal Physics Review, published in the journal Physics Review, Rev. B 97, 235113 (2018). The research work was awarded the National Key R&D Program by Magnetoresistance and Shubnikov–de Haas oscillations in layered Nb3SiTe6 thin flakes. Projects, support from the National Natural Science Foundation and the Hefei Science Center.