Friday, December 8, 2023

Two-gap topological superconductor LaB2 with excessive Tc = 30 Ok


Since two hole superconductivity was found in MgB2, analysis on multigap superconductors has attracted growing consideration due to its intriguing basic physics. In MgB2, the Mg atom donates two electrons to the borophene layer, leading to a stronger hole from the σ band and a weaker hole from the π bond. First-principles calculations display that the 2 hole anisotropic superconductivity strongly enhances the transition temperature of MgB2 as compared with that given by the isotropic mannequin. On this work, we report a three-band (B-σ, B-π, and La-d) two-gap superconductor LaB2 with very excessive Tc = 30 Ok by fixing the absolutely anisotropic Migdal–Eliashberg equation. Due to the σ and π–d hybridization on the Fermi floor, the electron–phonon coupling fixed λ = 1.5 is considerably bigger than the λ = 0.7 of MgB2. Our work paves a brand new route to reinforce the electron–phonon coupling energy of multigap superconductors with d orbitals. Then again, our Image ID:d3nh00249g-t1.gif evaluation reveals that LaB2 belongs to the weak topological semimetal class, resulting in a doable topological superconductor with the best Tc so far. Furthermore, upon making use of strain and/or doping, the topology is tunable between weak and robust with Tc various from 15 to 30 Ok, opening up a versatile platform for manipulating topological superconductors.

Graphical abstract: Two-gap topological superconductor LaB2 with high Tc = 30 K


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