Structural Characterization of CaFeAs Single Crystal and Quantum Oscillatometry Determination of Fermi Surface Structure (Right)
Obtaining electronic structure information is an important precondition for revealing the formation mechanism of unconventional superconductivity, but little is known about the electronic structure of 1111-type iron-based superconductors. Center for Excellence in Superconductivity, Chinese Academy of Sciences, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences Mu Gang, a member of the State Key Laboratory of Information Functional Materials, cooperated with the Taichi Terashima research group of Japan National Institute of Material Science and Technology. On the basis of successfully obtaining high-quality, large-size 1111 CaFeAsF single crystals in the early stage, Oscillation effect, for the first time to obtain electronic structure information of the material.Relevant research published in Physical Review X on the Fermi Surface with Dirac Fermions in CaFeAsF Determined via Quantum Oscillation Measurements.
As the earliest found iron-based high-temperature superconducting material with the highest transition temperature, the iron-based 1111 system has been lack of large-size and high-quality single crystal samples, which has restricted the further study on the physical problems related to this material system. The team just selected CaAs as a flux to grow a millimeter-sized, high-quality CaFeAsF precursor and a Co-doped superconductor single crystal, which laid the foundation for an in-depth study of the iron-based superconductor 1111. In addition, they presented to the Institute of Physics, Fudan University, Shanghai High Pressure Center, Wuhan Pulse Strong Field Center, Nanyang Technological University of Singapore, National Materials Research Institute of Japan and many other domestic and foreign research institutes to provide single crystal samples for cooperative research.Quantum oscillation experiments are based on the Schoeni- (SdH effect) requires that the electrons in the material have a long enough free movement time and high requirements on the sample quality. The high-quality single crystal samples grown by the Mou Gang team provide a guarantee for the smooth development of the experiment. Quantum Oscillation Measurement The material was found to have a very small Fermi surface (as shown in Fig. (D)), where the electron near the Fermi surface Has a Dirac-type dispersion relationship and the first non-trivial Berry phase in iron-based superconductors has been observed. This study is of great importance to further understand the electronic states of Fe-based superconducting 1111 system and its effect on superconducting behavior Promote the role.
Research has won the support of the National Natural Science Foundation of China and the Chinese Academy of Sciences Youth Innovation Association.
