(Correspondent: Hao Hu ,Yuan Cheng) On May 19, 《Nature·communication》(Nature Communications, impact factor of 11.47, DOI: 11.47 / NCOMMS15297) online published the paper entitled " Emptying Dirac valleys in bismuth using high magnetic fields " of team of Professor Zengwei Zhu who worked in Wuhan national High Magnetic Field Center (raising) in our school. Professor Zengwei Zhu is the first author and corresponding author, Dr Jinhua Wang as the second author of the study has made an important contribution, Dr Huakun Zuo and top foreign experts professor Kamran Behnia in Wuhan national High Magnetic Field Center (raising) involved in the related work of the paper.
Bismuth, as traditional semi-metal materials, play an important role in condensed matter physics, scientists found many important physical phenomenon around it, including the Seebeck effect, Nernst effect, quantum oscillation and great reluctance. As topology with low carrier material has been found, it has become a research hotspot that the phenomenon of three dimensional electron gas in low carrier materials represented by bismuth in high magnetic field in recent years, the research on transport properties of bismuth also received extensive attention in academia. Around these research hotspot, professor Zengwei Zhu team has conducted a thorough study of the strange behavior semi-metal Bismuth in the high magnetic field.
Bismuth single crystal in which there are three equivalent degrees of freedom with Dirac electronic pocket and valley, the Fermi level is lower, and the 9 tesla low magnetic field with the direction of trigonal can make electronic at last landau energy levels, achieving the quantum limit. When the magnetic field along the semi-metal bismuth crystal direction binary or bisectrix high symmetry, magnetic resistance fall sharply near the magnetic field of about 40 tesla suddenly, previous research suggests that the drastical reduce of magnetic resistance is caused by the Landau energy levels of the hole of leaving the Fermi surface. The team through the in-depth study of this phenomenon, dependent on the Angle of the binary - bisectrix magnetic resistance were measured, and in combination with theoretical calculation, proved that the magnetic resistance decline has direct relationship with Dirac valley, namely when the magnetic field is higher than the threshold Bempty, one or two Dirac valley will be completely emptying to another Dirac valley, the electron moves from high mobility rate of Dirac valley to the low mobility rate of Dirac valley, causing the conductivity increases multiply, resulting in a dramatic decrease in the magnetic resistance. At the same time, the study also confirmed that Bismuth is the first material of which the cyclotron energy is large enough to make the Fermi sea be cleared.
Professor Zeng wei Zhu was selected into "youth one thousand plan" in 2014 , he is not only the head of the transport station in Wuhan national High Magnetic Field Center, but also is a member of the high field physics institute, which is jointly founded by Wuhan national High Magnetic Field Center and the institute of physics. Professor Zeng wei Zhu has studied in the field of condensed matter physics for a long time, and now his main research direction is the physics under extreme conditions, such as extremely low temperatures and high magnetic field .In the two years since he returned to China, around the transportation behaviors in semi-metal, professor Zengwei Zhu has made full use of Wuhan national High Magnetic Field Center ‘s platform advantages and experimental conditions and carried out the relative research, his published academic papers in international authorities such as Physical Review Letters, Physical Review Letters, DOI: 10.1103 / PhysRevLett. 114.176601, 2015/05), Physical Review B, (Physical Review B, DOI: 10.1103 / PhysRevB. 95.014502, 2017/01) etc., sustainable production of high levels of achievement, enhancing the research level of Wuhan national High Magnetic Field Center, also promoting the rapid growth of graduate students in the team.
The study obtained support from the national "one thousand youth" program, the national natural science fund, the national key research and development plan, "111" plan and exchanging and high-end designed projects of our school.
