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

TL;DR

This paper investigates monolayer NbF$_4$, revealing its potential as a 4d^1 analogue of cuprates with antiferromagnetic and superconducting phases, using density functional theory and renormalization group methods.

Contribution

It demonstrates that monolayer NbF$_4$ exhibits cuprate-like electronic properties, including antiferromagnetism and d-wave superconductivity, as a novel 2D platform for high-$T_c$ superconductivity.

Findings

Energy band near Fermi level from $4d_{xy}$ orbital.

Undoped system is an antiferromagnetic insulator.

Doped system develops $d_{x^2-y^2}$-wave superconductivity.

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.