Dirac points with giant spin-orbit splitting in the electronic structure of two-dimensional transition-metal carbides

TL;DR

This paper predicts the existence of Dirac electrons with significant spin-orbit splitting in 2D transition-metal carbides (MXenes), highlighting their robustness and potential for Dirac physics applications.

Contribution

It introduces a theoretical discovery of Dirac electrons with giant spin-orbit splitting in MXenes, a new class of 2D materials not previously known for this property.

Findings

Twelve conical crossings in the Brillouin zone.

Giant spin-orbit splitting in Dirac points.

Protection of band structure in multilayer phases.

Abstract

Two-dimensional (2D) materials, especially their most prominent member, graphene, have greatly influenced many scientific areas. Moreover, they have become a base for investigating the relativistic properties of condensed matter within the emerging field of Dirac physics. This has ignited an intense search for new materials where charge carriers behave as massless or massive Dirac fermions. Here, we theoretically show the existence of Dirac electrons in a series of 2D transition-metal carbides, known as MXenes. They possess twelve conical crossings in the 1st Brillouin zone with giant spin-orbit splitting. Our findings indicate that the 2D band structure of MXenes is protected against external perturbations and preserved even in multilayer phases. These results, together with the broad possibilities to engineer the properties of these materials phases, make Dirac MXenes a potential candidate for studying and developing novel Dirac-physics-based technologies.