Prediction of hydrogen-induced high-temperature superconductivity in monolayer ScB2H2

Jialiang Cai; Zhengtao Liu; Zihao Huo; Wenxuan Chen; Guiyan Dong; Tiancheng Ma; Runxian Ji; Xin Wang; Defang Duan

doi:10.1103/wdg8-8km7

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Prediction of hydrogen-induced high-temperature superconductivity in monolayer ScB2H2

Jialiang Cai, Zhengtao Liu, Zihao Huo, Wenxuan Chen, Guiyan Dong, Tiancheng Ma, Runxian Ji, Xin Wang, Defang Duan

DOI 10.1103/wdg8-8km7 · Physical Review B

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Abstract

Light elements, such as hydrogen and boron, provide a possible route to high-temperature superconductivity. However, the pursuit of light-element superconductors with critical temperature (Tc) exceeding the McMillan limit at ambient pressure still remains challenging. Here, we design a two-dimensional (2D) superconductor, ScB2H2, via hydrogenation. This material features a unique sandwich structure where the scandium layer is asymmetrically functionalized with boron and hydrogen on opposite surfaces. The boron layer plays the key role in high-temperature superconductivity of ScB2H2 with the metallization of σ bands that induce a Van Hove singularity near the Fermi level. This enables strong coupling between the σ band and the in-plane vibration of B atoms, yielding a large electron-phonon coupling of 1.69. Remarkably, the monolayer ScB2H2 exhibits three-gap superconductivity with Tc of 51−61K (μ*=0.1−0.2), surpassing the McMillan limit. Although hydrogen is lighter than boron, the electron-phonon coupling of hydrogen layer is weaker than that of the boron layer. Nevertheless, hydrogen not only stabilizes ScB2H2 via hydrogenating naked activity Sc sites of monolayer ScB2, but also controls the metallization of the σ band in the honeycomb B sublattice. Our finding provides a theoretical guidance for regulating the 2D superconductivity through functionalizing two faces of 2D materials with light elements.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
ScB2H2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	51	Pressure unresolved	unknown
ScB2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	20.4	Pressure not reported	unknown
MgB2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	39	Pressure unresolved	unknown
MgB2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	18	Pressure not reported	unknown
MgB4 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	52	Pressure not reported	unknown
CaB2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	41.6	Pressure not reported	unknown
AlB2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	26.5	Pressure not reported	unknown
MoSH Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	28.6	Pressure not reported	unknown
PC3 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	31	Pressure not reported	unknown
MgB2H Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	67	Pressure not reported	unknown
CaB3H Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	39.3	Pressure not reported	unknown
H3S Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	203	Pressure not reported	unknown
LaH10 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	250	Pressure not reported	unknown
Pb Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	1.8	Pressure not reported	unknown