Origin of Ferroelectricity and Superconductivity with Nontrivial Electronic Topology in Fluorinated Nb2N

TL;DR

This study predicts and analyzes fluorinated Nb2N monolayers as 2D materials exhibiting both superconductivity and ferroelectricity with nontrivial topological properties, offering potential for electrically controllable quantum devices.

Contribution

First principles calculations reveal fluorinated Nb2N monolayers as novel 2D materials with coexisting superconductivity, ferroelectricity, and nontrivial band topology, expanding the landscape of quantum materials.

Findings

H3-Nb2NF2 exhibits vertical ferroelectricity.

H1-Nb2NF2 shows superconductivity with Tc of 32 K.

Both structures possess nontrivial topological band features.

Abstract

Two-dimensional (2D) intrinsic superconductors with nontrivial topological band and vertical ferroelectricity exhibit fascinating characteristics to achieving electrostatic control of quantum phases. While, only a few such 2D materials have been theoretically predicted. In this work, based on first principles calculations, we explore the superconductivity and ferroelectric properties in fluorinated 2D Nb2N. In the stable Nb2NF2, H3-Nb2NF2 breaks the spatial inversion symmetry, exhibiting vertical ferroelectric. More interestingly, it not only possesses intrinsic superconductivity with superconducting transition temperatures (Tc) of 10 K, but also exhibits nontrivial band topology. While, H1-Nb2NF2 shows topological band and superconductivity with Tc of 32 K, surpassing most of 2D conventional topological superconductors' candidates. Our research has enriched 2D superconducting materials with nontrivial band topology and ferroelectric properties, and provided a theoretical basis for the preparation of devices switching between superconducting and ferroelectric states with external electric field.