Lattice, Charge, Spin and Orbital Aspects of the Iron Chalcogenide Superconductors

18 May 2021


Professor Wei Bao delivered an online lecture for the Hong Kong Institute for Advanced Study.

Professor Wei Bao, Chair Professor of Department of Physics at City University of Hong Kong (CityU), delivered a lecture titled “Lattice, Charge, Spin and Orbital Aspects of the Iron Chalcogenide Superconductors” at the last online talk of the Hong Kong Institute for Advanced Study (HKIAS) Lecture Series on Physics at CityU on 12 May 2021.

Superconductivity, discovered slightly more than one hundred years ago in simple metals, is a phenomenon whereby a charge moves through a material without resistance and is associated with icy temperatures. In the talk, Professor Bao discussed the grand challenge and significance of superconductivity.

Professor Bao started with a brief historical introduction to superconductivity and explained the elementary properties of superconductors. He highlighted that the superconductor has zero resistance, perfect diamagnetism, isotope effect, and energy gap at the Fermi surface.

Subsequently, Professor Bao introduced the finding of high-temperature superconductivity in normally insulating cuprate ceramics. He stressed that this breakthrough discovery has led to an iron age of superconductors. Recently, iron chalcogenide superconductors have become one of the most investigated superconducting materials since it was found a decade ago.

Moreover, Professor Bao reviewed and explained the structure and order of lattice, charge, spin and orbital degrees of freedom of electrons in condensed matter. He hoped scientists could use billions of electrons and atoms to make superconductors at room temperature soon. That ability would be transformative for technological applications.

Professor Bao’s research focuses on using the neutron scattering technique as the main research tool to investigate various frontier issues of correlated electronic systems in condensed matter, and these including the Mott metal-insulator transition, colossal magnetoresistivity, orbital ordering, re-entrant spin-glass state, itinerant antiferromagnetism, low-dimensional quantum antiferromagnetism, and unconventional superconductivity in heavy-fermion, cuprate, and iron-based materials, often under the extreme condition at low temperature, high pressure and high magnetic field.

Professor Bao obtained his Ph.D. from the Johns Hopkins University in the USA. He worked as a consultant in AT&T Bell Laboratories and a Postdoctoral Associate in Brookhaven National Laboratory before joining the Los Alamos National Laboratory as a Technical Staff. He was a Distinguished University Professor at the Renmin University of China in Beijing.

In addition to leading major research projects of the CNNSF and 973 Program in China, he has led a major national research infrastructure project in building a suite of innovative cold neutron spectrometers in Beijing. Besides, Professor Bao was nominated as a Fellow of American Physical Society "for neutron scattering studies of the magnetic structure and spin dynamics of highly correlated electron systems".

This lecture is supported in part by the Kwang Hua Educational Foundation.

  (Right) Professor Jacob Huang, Executive Director of HKIAS and Chair Professor of Department of Materials Science and Engineering, presented a souvenir to (left) Professor Bao. (From left) Professor Huang, Professor Bao, Professor King-Ning Tu, Chair Professor of Department of Materials Science and Engineering and Department of Electrical Engineering at CityU and Professor Xun-Li Wang, Head and Chair Professor of Department of Physics at CityU.  

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