Orbital-selective superconductivity via interlayer electron transfer in the two-dimensional borides MB3 (M=Mg, Al, Ca, Sc, Y, and In)

Shengnan Bi; Fei Li; Guochun Yang

doi:10.1103/df4q-m1d3

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Orbital-selective superconductivity via interlayer electron transfer in the two-dimensional borides MB3 (M=Mg, Al, Ca, Sc, Y, and In)

Shengnan Bi, Fei Li, Guochun Yang

DOI 10.1103/df4q-m1d3 · Physical Review B

T1

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Abstract

Superconductivity in layered metal borides originates from strong coupling between σ-bonding electrons and in-plane phonon modes. Herein, we demonstrate that layer-resolved σ-orbital occupancy governs the superconducting behavior of two-dimensional C (M=Mg, Al, Ca, Sc, Y, and In). The inequivalent chemical environments of the threefold-coordinated B1 layer and sixfold-coordinated B2 layer induce different degrees of charge transfer, resulting in layer-dependent σ-orbital filling. Partially filled B1 σ orbitals provide the fundamental electron-phonon coupling across the designed structures, whereas filling states of B2 σ orbitals dictates the variation of Tc. When B2 σ orbitals remain partially filled, both boron layers contribute cooperatively to electron-phonon coupling, yielding Tc values above 30 K in CaB3, InB3, and MgB3. In contrast, saturation of the B2 σ orbital drives charge redistribution toward B1 layers, suppressing B2 contribution and lowering Tc below 15 K in YB3, ScB3, and AlB3. These results identify orbital-selective σ-band occupancy, mediated by layer-specific charge transfer, as a microscopic principle for tuning superconductivity in boride materials.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
CaB3 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	39.77	Pressure unresolved	unknown
InB3 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	31.4	Pressure unresolved	unknown
MgB3 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	31.3	Pressure unresolved	unknown
YB3 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	15.02	Pressure unresolved	unknown
ScB3 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	6.27	Pressure unresolved	unknown
AlB3 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	3.31	Pressure unresolved	unknown
MgB2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	39	Pressure not reported	unknown
SrB3C3 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	43	Pressure not reported	unknown
CaB2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	48	Pressure not reported	unknown
MgB3C3 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	59	Pressure not reported	unknown
Li0.5BC Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	100	Pressure not reported	unknown
LiC6 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	8.1	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