Beijing Institute of Mathematical Sciences and Applications

Zheng Wei Liu , Shing-Tung Yau , Hui Zhao

Hong Ding

Tuesday, March 1, 2022 2:00 PM - 4:00 PM

中会议室一

Tencent 336 497 186 (2022)

Majorana zero modes (MZMs) in solid materials and devices have attracted tremendous interest owing to their potential applications in robust quantum computation. Last ten years witness rapid progresses and serious setbacks in searching for MZMs. 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) with Tc ~ 15K by using ARPES [1], and a pristine MZM inside a vortex core of this material by using STM [2]. We have observed a half-integer level shift of vortex bound states [3] and nearly quantized Majorana conductance [4] in this material, which are hallmarks of MZMs. We have also found that most of iron-based superconductors [5], including monolayer Fe(Te, Se)/STO [6], have similar topological electronic structures. One of them, CaKFe4As4, an Fe-As bilayer superconductor (Tc ~ 35K), is found to possess MZM and other bound states that can be well reproduced by a simple theoretical model [7]. Finally, we found that pressure can be used as a good tuning method to control MZMs in FeSCs [8,9]. 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 a 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 [10]. [1] Peng Zhang et al., Science 360, 182 (2018) [2] Dongfei Wang et al., Science 362, 334 (2018) [3] Lingyuan Kong et al., Nature Physics 15, 1181 (2019) [4] Shiyu Zhu et al., Science 367, 189 (2020) [5] Peng Zhang et al., Nature Physics 15, 41 (2019) [6] Xun Shi et al., Science Bulletin 62, 503 (2017) [7] Wenyao Liu et al., Nature Communications 11, 5688 (2020) [8] Lingyuan Kong et al., Nature Communications 12, 4146 (2021) [9] Wenyao Liu et al., arXiv:2111.03786 [10] Lingyuan Kong and Hong Ding, Acta Physica Sinica 69, 110301 (2020)

Hong Ding, a professor of the Institute of Physics (IOP), Chinese Academy of Sciences, and the Chief Scientist of Beijing National Laboratory for Condensed Matter Physics. 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 as an assistant, associate and full professor during 1998 - 2008. He joined IOP full time in 2008. 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. His achievements have been selected as Top Ten Scientific Advancements in China and/or Top Ten News of Science and technology in China of years 2015, 2017, and 2018. He has published more than 280 papers with total citations over 27000 (Google Scholar). He received Sloan Research Fellowship Award in 1999, was elected as American Physical Society Fellow in 2011, received European Advanced Materials Award in 2018，was selected as CCTV Science and Technology Annual Innovation Figures in 2018, and received Outstanding Science and Technology Achievement Prize (Individual Prize) of Chinese Academy of Sciences in 2020.