Design Principles for High-Temperature Superconductors with a Hydrogen-Based Alloy Backbone at Moderate Pressure (2024)

Hydrogen-based superconductors provide a route to the long-sought goal of room-temperature superconductivity, but the high pressures required to metallize these materials limit their immediate application. For example, carbonaceous sulfur hydride, the first room-temperature superconductor made in a laboratory, can reach a critical temperature ($T_c$) of 288K only at the extreme pressure of 267GPa. The next recognized challenge is the realization of room-temperature superconductivity at significantly lower pressures. Here, we propose a strategy for the rational design of high-temperature superconductors at low pressures by alloying small-radius elements and hydrogen to form ternary H-based superconductors with alloy backbones. We identify a “fluorite-type” backbone in compositions of the form $AX{\mathrm{H}}_8$, which exhibit high-temperature superconductivity at moderate pressures compared with other reported hydrogen-based superconductors. The $Fm\overline{3}m$ phase of ${\mathrm{LaBeH}}_8$, with a fluorite-type H-Be alloy backbone, is predicted to be thermodynamically stable above 98GPa, and dynamically stable down to 20GPa with a high $T_c\sim 185\mathrm{K}$. This is substantially lower than the synthesis pressure required by the geometrically similar clathrate hydride ${\mathrm{LaH}}_{10}$ (170GPa). Our approach paves the way for finding high-$T_c$ ternary H-based superconductors at conditions close to ambient pressures.

• Received 15 May 2021
• Revised 28 September 2021
• Accepted 24 December 2021

DOI:https://doi.org/10.1103/PhysRevLett.128.047001

Condensed Matter, Materials & Applied Physics

Zihan Zhang¹, Tian Cui^2,1,*, Michael J. Hutcheon³, Alice M. Shipley³, Hao Song¹, Mingyang Du¹, Vladimir Z. Kresin⁴, Defang Duan^1,†, Chris J. Pickard^5,6, and Yansun Yao⁷

• ¹State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China
• ²Institute of High Pressure Physics, School of Physical Science and Technology, Ningbo University, Ningbo 315211, China
• ³Theory of Condensed Matter Group, Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
• ⁴Lawrence Berkeley Laboratory, University of California, Berkeley, California 94720, USA
• ⁵Department of Materials Science & Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom
• ⁶Advanced Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba, Sendai 980-8577, Japan
• ⁷Department of Physics and Engineering Physics, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E2, Canada

• ^*Corresponding author.cuitian@nbu.edu.cn
• ^†Corresponding author.duandf@jlu.edu.cn