Template-guided design of thermodynamically stable sp3-hybridized metal boride with 90 K superconductivity under high pressure

Abstract

Strongly covalent-bonded metallic compounds have emerged as promising high-temperature superconductors since the discovery of record-holding 39 K superconductivity in MgB2. Yet, recent theoretically designed lightweight high-critical temperature (Tc) covalent superconductors lack thermodynamic stability, a key prerequisite for experimental validation. Herein, we propose an effective template-guided strategy, designing nine fully σ-bonded metal boride superconductors with Tc exceeding MgB2. Machine-learning accelerated structure searches combined with anharmonic calculations confirm F4¯3m−Sr2B5 to be thermodynamically stable at 38–54 GPa and retain dynamic stability at ambient conditions. The calculated Tc reaches around 90 K at 40 GPa, dominated by strong coupling between the metallized σ electronic states and E phonon modes of boron atoms. Our design concept may advance the development of high-Tc lightweight covalent superconductors that can survive at room pressure.

Source-reported materials — not catalogue approval

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