讲座题目：Informatics-enabled high-throughput ab initio prediction of superconducting hydrides and ferroelectrics

讲座嘉宾：Yuewen Fang postdoc at the University of the Basque Country

讲座时间：2024年7月13日 10:00

讲座地点：唐敖庆楼B区521报告厅

讲座嘉宾

Yuewen Fang holds a PhD in physical electronics under the supervision of Prof. Chun-Gang Duan. Currently he is a postdoc at the University of the Basque Country. He is setting a transition to a tenured scientist and an associate professor of the Spanish National Research Council, and will lead the Laboratory of Quantum Theory of Materials together with Ion Errea. Prior to moving to Spain, Yuewen was a program-specific researcher at Kyoto University and Tokyo Institute of Technology from 2017 to 2021.

Yuewen's research interests include materials theory and materials discovery of thermoelectrics, superconductors, multiferroics, ferroelectrics, polar metals, and complex interfaces. His research work has resulted in more than 50 publications in prestigious journals such as Science, JACS, Nature Communications, Advanced Materials, and more. He was awarded the 2021 Outstanding Reviewer Awards by Institute of Physics (IOP) Publishing and the European Physical Society award at the Conference on Computational Physics 2023.

Abstract

The development of supercomputers and computational methods has enabled the high-throughput prediction of functional materials. In this talk, I will focus on two highly sought-after classes of materials: superconducting hydrides and ferroelectrics.

The recent report by Dasenbrock-Gammon et al. on the near-ambient superconductivity in N-doped lutetium hydride (Lu-N-H) [Nature 615, 244–250 (2023)] has gained much attention due to its enormous promise in applications. However, we evidenced the absence of high-temperature superconducting Lu-N-H at 1 GPa and foud that the doped N atoms favor insulating behavior rather than metallic properties [1,2]. Despite the absence of room-temperature superconductivity at 1 GPa, we find that cubic Lu₄H₁₁N exhibits a high Tc of 100 K at 20 GPa, a large increase compared to 30 K in its parent LuH₃ at the same pressure. In addition, the LuH₁₀ and LuH₆ become high-temperature superconductors at 175 GPa and 100 GPa, with Tc of 286 K and 246 K, respectively.

While high-temperature superconductivity is predicted to be unattainable in Lu-based hydrides at 1 GPa, we performed a machine learning search of more than 1 million compounds and predicted a series of ambient-pressure high-Tc superconducting hydrides [3]. Our high-throughput ab initio electron-phonon coupling study finds around 50 superconducting hydrides with a critical temperature above 20 K. In particular, a family of compounds with composition Mg₂XH₆ where X=Rh, Ir, Pd, or Pt exhibit superconductivity in the range of 45-80 K and are (nearly) thermodynamically stable[4].

Besides, we have designed ferroelectric ultrathin films based on bismuth oxide [5]. The thin films with thicknesses that range from 1 to 4.56 nanometers possess a relatively large remanent polarization from 17 to 50 microcoulombs per square centimeter. We further implemented the ferroelectric tunnel junctions based on the designed ultrathin films of ferroelectrics and found the junctions based on 1 nm thin films can maintain giant tunnelling electroresistance of 7 ×10⁵. These ferroelectric tunnel junctions demonstrate up to 32 resistance states without any write-verify technique. They also show high endurance (over 5 ×10⁹), high linearity of conductance modulation, and long retention time (10 years).

[1] Ð. Dangic, P. Garcia-Goiricelaya, Y.-W. Fang, et al., Physical  Review B 108, 064517 (2023)

[2] Y.-W. Fang*, Ð. Dangic*, and Ion Errea*, Communications Materials 5, 61 (2024)

[3] T. F. T. Cerqueira, Y.-W. Fang, I. Errea, et al., Advanced Functional Materials 2404043 (2024)

[4] A. Sanna, T. F. T. Cerqueira, Y.-W. Fang, et al., npj Computational Materials npj Comput Mater 10, 44 (2024)

[5] Q. Yang†, J. Hu†, Y.-W. Fang†, et al., Science 379, 1218 (2023)

[6] Y. Jia†, Q. Yang†, Y.-W. Fang*, et al., Nature Communications 15, 693 (2024)