Dr. Chenglin Zhang [University of Rice, USA]
Time: 2:00 pm, April 30, 2014
Place: HPSTAR Meeting Room (Shanghai)
Title: Neutron scattering study on NaFe1-xCoxAs"
Abstract:
Since the discovery of iron superconductors, the (Ba,Sr,Ca)Fe2As2 (122) family especially electron doped side has been subjected to heavily study by neutron scattering. One of the pronounced features generally observed in bulk superconducting compositions is a broad resonance along antiferrromagnetic order wave vector. The resonance energy linearly scales with Tc. However, our neutron study shows that Co-doped NaFeAs system exhibits complexity, distinguishing itself from 122 system. We observed a sharp resonance in the electron-overdope regime, providing strong evidence for S+- pairing symmetry in pnictide superconductors. In the underdoped regime, we find double resonances at commensurate wave vector, demonstrating the multi-orbital nature of pnictides. Our finding further suggests that the resonance energy and Tc may not be simply correlated in multiband superconductors such as iron pnictides.
Bio. of Dr. Chenglin Zhang:
Dr. Chenglin Zhang once worked as research assistant professor in the University of Tennessee, USA, and is now doing research work as researcher in the Department of Physics at Rice University. He got his Ph.D Degree at Rutgers University (New Jersey) in 2008.
Since 2008, Dr. Zhang and his co-workers have systematically developed the iron-based superconductor and applied neutron scattering into the research of the correlation between the magnetic excitation and superconductivity. Sharp magnetic resonance peak has been discovered in the co-doped NaFeAs system, which proves the mechanism of superconducting pairing. Double resonance peak has been especially discovered in the underdoped area for the first time, revealing the multi-track characteristics of iron. During his doctoral study, his exploration on new materials was reported by international science media as a bright spot for several times, including Nature Materials, Applied Physics Letter and Science Daily.
Until now Dr. Zhang and his co-workers have published about 60 SCI papers, which have been cited for over 1800 times.