Prof. Xu Gang Make Progress in Research on Topological Semimetal

October 30, 2017

On 19th September, the article which was titled “Topological Semimetal in Honeycomb Lattice LnSI” by Dr. Xu Gang, a professor at the Wuhan National High Magnetic Field Centre (WHMFC) of HUST, was published online in the world leading journal Proceedings of the National Academy of Science (PNAS). The research was a collaboration between Prof. Xu Gang, Dr. Nie Simin at Stanford University, Prof. Fritz B. Prinz, and Prof. Zhang Shou-cheng. Prof. Xu Gang was the corresponding author of the article, and HUST was the signature unit of the first author.


As a new quantum state, topological semimetal has received world-wide attention because of its special electronic model, such as the existence of Fermi arc, and its potential application value of future spintronic devices. Research about topological semimetal holds great significance for both fundamental physics and applied physics. From raising hypotheses to conducting experiments, Weyl semimetal, like HgCr2Se4 and TaAs, has received growing attention in research about condensed matter physics.


However, most of the previously reported Weyl semimetal exhibits rather complicated electronic band structures where Weyl nodes coexist with normal Fermi surfaces, which in turn have raised questions regarding the experimental observation of Fermi arc and the underlying physics research of negative magnetoresistance. Hence researchers are eager to find an ideal Weyl semimetal with a simple electronic band structure.


For this purpose, Prof. Xu Gang and his collaborators constructed a special honeycomb lattice model and conducted theoretical studies and research on its topological property. They found that promising topological phases could be realized in this model, including ideal Weyl semimetal structures, 3D strong topological insulators, nodal-line semimetal configurations, and a semimetal featuring both Weyl nodes and nodal lines. Guided by this model and the first principles calculations, they noticed that the electronic structures of LuSI, YSI and GdSI fit entirely into the model and enjoyed the special topological property. They showed that GdSI, the long-perceived ideal Weyl semimetal, had two pairs of Weyl nodes residing at the Fermi level and that both LuSI and YSI were strong topological insulators. Their work provided a mechanism to study topological semimetals and proposed a platform for exploring the physics of Weyl semimetals as well as related device designs.


Prof. Xu Gang returned to China and started to work as a professor at HUST in October 2016, and was recruited into the “National Thousand-Young-Talents Program of China” in 2017. Now, he works as the director of the Institute of Physics at WHMFC and focuses on the studies and research on materials computation and condensed matter theory. Before this, Prof. Xu Gang had made many academic achievements in areas like the iron-based superconductors and topological states. 35 papers were included in the Science Citation Index (SCI), 15 of which were published on the high level international journals, such as Physical Review Letters and Nature. His research achievements in topological materials and topological states included: 1. Generalized the topological classification from insulator to semimetal, and first proposed the concept of double-Weyl semimetals (Phys. Rev. Lett 107, 182806); 2. Gave two new proposals to realize the QAH effect (Nano letters 15 (3), 2019-2023Phys. Rev. Lett 115, 186802); 3. Gave two new proposals to realize the topological superconducting state (Phys. Rev. Lett 117, 047001).


Since he entered the HUST, Prof. Xu Gang has taken advantage of the platform provided by WHMFC and done many cooperative studies with teachers from the School of Physics at HUST. They established research teams working on high magnetic field studies, constructed simulation platform for scientific calculation, and actively conducted scientific research in the area of condensed matter physics, offering the theoretical foundation for physical experiments in the high magnetic field and promoting the development of cutting-edge and fundamental research about the high magnetic field.


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