High Transition Temperature Driven by Type-II Dirac Fermions in Topological Superconductor B7Be2B7 Nanosheet

Meng-Hui Wang; Zhengxuan Wang; Guangtao Wang; Haolin Song; Yuhao Fu; Lu Li; Zhong-Hua Cui

doi:10.1021/acs.nanolett.4c02497

High Transition Temperature Driven by Type-II Dirac Fermions in Topological Superconductor B₇Be₂B₇ Nanosheet

Nano Lett. 2024 Sep 16. doi: 10.1021/acs.nanolett.4c02497. Online ahead of print.

Authors

Meng-Hui Wang¹, Zhengxuan Wang², Guangtao Wang², Haolin Song¹, Yuhao Fu³, Lu Li⁴, Zhong-Hua Cui^{1

5}

Affiliations

¹ Institute of Atomic and Molecular Physics, Jilin University, Changchun 130023, China.
² College of Physics, Henan Normal University, Xinxiang, Henan 453007, China.
³ State Key Laboratory of Superhard Materials, International Center of Computational Method and Software, College of Physics, Jilin University, Changchun 130023, China.
⁴ College of Chemistry, Jilin University, Changchun 130023, China.
⁵ Key Laboratory of Physics and Technology for Advanced Batteries (Ministry of Education), Jilin University, Changchun 130023, China.

PMID: 39283029
DOI: 10.1021/acs.nanolett.4c02497

Abstract

Topological superconductors (TSCs) offer a promising avenue for delving into exotic states of matter and fundamental physics. We propose a strategy for realizing high transition temperatures (high-T_c) in TSCs by leveraging nontrivial topology alongside a high carrier density near the Fermi level in metal-doped borophenes. We identified 39 candidates with exceptional thermodynamic stability from thousands of Be-intercalated borophenes (Be_1-xB_x) via extensive structural searches. Seven candidates exhibit high carrier densities, with B₇Be₂B₇ emerging as a particularly promising candidate. This nanosheet displays both type-I and type-II Dirac fermions, indicative of $Z_{2}$ topological metals, thereby positioning it as an ideal platform for high-T_c TSCs. The high-density π electrons of B₇Be₂B₇ originating from type-II Dirac fermions, coupled with the out-of-plane vibrations of B and Be atoms, significantly enhance the electron-phonon coupling (λ = 1.42), resulting in a substantially high-T_c of 31.5 K. These findings underscore the potential of metal-doped borophenes as a cutting-edge material platform for achieving high-T_c TSCs.

Keywords: high transition temperature; metal-doped borophenes; topological superconductors; type-II Dirac fermion.