Emergent two-dimensional superconductivity in few-layer stanene

The two-dimensional crystalline superconductors possess a variety of exotic properties such as the Griffiths singularity, the quantum metal phase as well as the strongly enhanced in-plane critical field [1]. Here we report the discovery of superconductivity in few layer stanene—ultrathin gray tin (111)—and the complete phase diagram in the magnetic field and temperature plane. The emergence of superconductivity in stanene is unexpected. Bulk gray tin is non-superconductive [1] and stanene attracts attention mostly because of its topological properties. Instead, we found superconductivity by growing few-layer stanene on PbTe/Bi₂Te₃/Si(111) substrate via molecular beam epitaxy [2][3]. The superconducting properties can be further modulated by varying the substrate thickness. Our experimental studies are further supported by first-principles calculations, which suggest that superconductivity occurs in a doped quantum spin Hall insulator.


References
[1] Y. Saito, T. Nojima and Y. Iwasa, Nat. Rev. Mater. 2, 16094 (2017).
[2] M. Liao^#, Y. Zang^#, et al. Nat. Phys. 14, 344-348 (2018).
[3] Y. Zang, et al. Adv. Funct. Mater. 28, 1802723 (2018).