Two‑Dimensional Superconductors

Superconductivity was among the properties of graphene, the 2D wonder material opening the way for superconducting device and quantum memory qubits. Nowadays, other 2D materials reach much higher superconducting temperatures. 2D materials (Janus chalcogenides, boride monolayers, MXenes) can host phonon‑mediated superconductivity at remarkable temperatures for atomically thin systems. They are grown experimentally with chemical vapour deposition, but this is challenging and calculations are the best way to determine what might be worth making.

structure — 2D materials are in fact trilayers, typically with light elements like sulphur and hydrogen top and bottom, and heavy metals like molybdenum in the middle.

strain and holes — Calculation of superconductivity uses Eliashberg theory: first we calculate which electrons can move easily (the "Fermi surface", then we calculate if vibrations of the atoms can pair up these electrons so they move together and cannot be scattered: this is superconductivity.

We considered many permutations, across published and arXiV papers

WSeH and WSH are predicted to have Tc=9.23K and 10.52K

Permutations of (Ti,Zr, Hf)(S,Se,Te)H have predicted Tc in the 20-30K range. They also have magnetic states, which may be metallic, half-metallic or semiconduting. We predict that magentism will be preferred to superconductivity in all cases except HfSH and HfSeH.

Hydrogenated borides (Sc,Y,V,Nb)B2Hx are variants of the BCS superconductor MgB2. The calculations show Tc 69 K and 83 K for Nb2B2H4 and V2B2H4, respectively.

Two‑Dimensional Superconductors

References