Dr. Hong Ding - Institute of Physics, Chinese Academy of Sciences
Iron-based superconductors (Fe-SCs), with their highest transition temperature (Tc) at 57K, have been added since 2008 to the family of high-Tc superconductors which has been solely occupied by copper-based superconductors (Cu-SCs) for more than 20 years. Both Fe-SCs and Cu-SCs, with a transition element playing crucial roles in their superconductivity, share a similar phase diagram where the superconducting phase is adjacent to a magnetic order phase, and are clearly beyond of the scope of BCS superconductors. In this talk I will report our extensive and some new ARPES results on Fe-SCs, which demonstrate unequivocally that a strong pairing gap is determined by its location in the momentum space, basically following a coskxcosky function which is likely determined by the local next-nearest-neighboring antiferromagnetic exchange J2, in much the same way that the d-wave gap of cuprates is caused by its nearest-neighboring exchange J1. In an example of Li(Fe,Co)As, the low-energy spin fluctuations, while sensitive to the Fermi surface nesting condition, are found not directly tie to its superconductivity. We conclude that a same pairing mechanism, at least phenomenologically if not microscopically, must be in work for both Fe- and Cu-SCs. Professor
Hong Ding obtained his BS degree in physics from Shanghai Jiao Tong University in 1990 and his PhD degree in physics from University of Illinois at Chicago in 1995. He was a Postdoctoral Fellow in Argonne National Laboratory from 1996 to 1998. He joined the Department of Physics at Boston College as an assistant professor in 1998, and became an associate professor in 2003 and a full professor in 2007. He joined IOP full time in 2008. Over the past 20 years, he has made important contributions to understanding of high temperature superconductors (including cuprates and iron pnictides) by measuring their electronic structure and superconducting gap using angle-resolved photoelectron spectroscopy. He has published more than 150 papers with a total citation number over 6000 and the H-index of 40, and has given more than 70 invited talks in international scientific conferences. He has received Aladdin Lamp Award from the Synchrotron Radiation Center, Wisconsin in 1995, Sloan Research Fellowship Award in 1999, Distinguished Research Award from Boston College in 2003, and was elected as APS Fellow in 2011.
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