Monolayer NbF${}_4$: a $4d^1$-analogue of cuprates

Abstract

The electronic structure and possible electronic orders in monolayer NbF${}_4$ are investigated by density functional theory and functional renormalization group. Because of the niobium-centered octahedra, the energy band near the Fermi level is found to derive from the $4d_{xy}$ orbital, well separated from the other bands. Local Coulomb interaction drives the undoped system into an antiferromagnetic insulator. Upon suitable electron/hole doping, the system is found to develop $d_{x^2-y^2}$-wave superconductivity with sizable transition temperature. Therefore, the monolayer NbF${}_4$ may be an exciting $4d^1$ analogue of cuprates, providing a new two-dimensional platform for high-$T_c$ superconductivity.

5 pages, 6 color figures