Dr. Nan-Lin Wang
International Center for Quantum Materials, School of Physics, Peking University
Optical spectroscopy is a primary experimental technique to probe the charge excitations and dynamical properties of electronic materials. In this talk I shall present our recent infrared spectroscopy study on ZrTe5 single crystals. The measurement at zero magnetic field reveals a linear rising of the optical conductivity with frequency over a relatively broad frequency range, being indicative of 3D massless Dirac dispersion. When magnetic field is applied, we observe clearly transitions between Landau levels in optical reflectance spectra. The transition energies follow the sequence of 1:(1+√2):(√2+√3):… and are proportional to the square root of the magnetic field in the low field regime, which are also hallmarks of massless Dirac fermions. It is also found that an exceptionally low magnetic field (less than 1 Tesla) is capable of driving the compound into its quantum limit. Most significantly, the splitting of Landau levels at higher magnetic field is explicitly identified in the reflectance data. Theoretical analysis of experimental data suggests that the ZrTe5 compound could be tuned from a 3D Dirac semimetal to a line-node or Weyl semimetal with Zeeman field along the crystalline b- or c-axis.
------------------------
Nan-Lin Wang obtained PhD degree in condensed matter physics from the University of Science and Technology of China in 1992. He was a professor in Institute of Physics (IOP, CAS) between 2000-2014 where he led a group exploring novel superconducting and other strongly correlated materials, growing single crystals and investigating their physical properties (primarily with optical spectroscopic techniques). He moved to the International Center for Quantum Materials (ICQM) in the School of Physics, Peking University in 2014 as a Chair Professor. Nan-Lin Wang has coauthored over 200 papers (including12 in Nature subjournals, 31 in PRL, 97 in PRB) and presented more than 80 invited talks in international conferences and workshops. He is among the list of Thomson Reuters Highly Cited Researchers (2014). He was a Member of C5 Commission (Low Temperature Physics) of the International Union of Pure and Applied Physics (IUPAP) (2008-2014). He was elected a Fellow of the American Physical Society in 2012.
Read More