Majorana zero modes (MZMs) in solid materials and devices have attracted tremendous interest owing to their potential applications in robust quantum computation. Recently iron-based superconductors (FeSCs) emerged as a new and promising Majorana platform due to relatively high temperature and high purity. In this talk I will report a series of our discoveries which help to establish this iron-Majorana platform. We have observed a superconducting topological surface state of Fe(Te,Se) by using ARPES, and a pristine MZM inside a vortex core of this material by using STM. We have observed a half-integer level shift of vortex bound states and nearly quantized Majorana conductance in this material, which are hallmarks of MZMs. We have also found that most of iron-based superconductors have similar topological electronic structures. Finally, we found that pressure can be used as a good tuning method to control MZMs in FeSCs. The combination of intrinsic topological nature of vortex and large energy spacing among the discreet bound states, all of which can be tuned by pressure, offers compelling evidence for proving the Majorana nature of vortex zero-modes discovered in FeSCs, thus creating an exciting playground for realizing and manipulating Majorana modes.
 

Hong Ding, a chair professor of Tsung-Dao Lee Institute, Shanghai Jiao Tong University. He obtained BS degree in physics from Shanghai Jiao Tong University in 1990 and 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 was a faculty member of Department of Physics at Boston College during 1998 - 2008. He was a Chief Scientist at the Institute of Physics, Chinese Academy of Sciences (CAS) during 2008 - 2022. He has made several significant scientific achievements, including discovery of pseudogap in cuprate superconductors, observation of s-wave superconducting gap in iron-based superconductors, discovery of Weyl fermions in solids, and discovery of Majorana zero modes in iron-based superconductors. He has published more than 300 papers with total citations over 20000. He received Sloan Research Fellowship Award in 1999, was elected as American Physical Society Fellow in 2011, received Outstanding Science and Technology Achievement Prize (Individual Prize) of CAS in 2020, selected as New Cornerstone Investigator in 2022, and elected as an academician of CAS in 2023.

Please contact phweb@ust.hk should you have questions about the talk.