Na2C monolayer : A novel 2p Dirac half-metal with multiple symmetry-protected Dirac cones

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review

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Author(s)

  • Wei-Xiao Ji
  • Bao-Min Zhang
  • Shu-Feng Zhang
  • Chang-Wen Zhang
  • Meng Ding
  • Pei-Ji Wang

Related Research Unit(s)

Detail(s)

Original languageEnglish
Pages (from-to)13645-13651
Journal / PublicationNanoscale
Volume10
Issue number28
Online published20 Jun 2018
Publication statusPublished - 28 Jul 2018

Abstract

A Dirac half-metal material, which has a gapped band structure in one spin channel but Dirac cones in the other, combines two intriguing properties of 100% spin polarization and massless Dirac fermions and has recently started to attract increasing attention. In this work, using first-principles calculations we predict that the disodium carbide (Na2C) monolayer is an intrinsic 2p Dirac half-metal material with 12 fully spin-polarized and symmetry-protected Dirac cones, and a slightly gapped (53 meV) spin-polarized nodal line coexisting in one spin channel, leaving the other spin channel insulated with a gap of 1.9 eV. There are two kinds of Dirac cones in Na2C, protected by different crystalline symmetries, both of which are robust against biaxial strains (±5%) and spin-orbit coupling effects, with Fermi velocities of up to 5.2 × 105 m s-1. Ferromagnetism is mainly contributed to by the unpaired 2p electrons in the carbon, with a Curie temperature estimated to be 382 K, and the origin of the 2p magnetism could be explained by the superexchange mechanism between C2- anions with the Na+ cation as a bridge. Our results not only indicate a promising candidate for high-speed spintronic devices, but also reveal the hidden mechanism of the origin of symmetric protection and ferromagnetic exchange interactions in a Dirac semi-metal, which would provide a feasible strategy for the design of Dirac materials.

Citation Format(s)

Na2C monolayer : A novel 2p Dirac half-metal with multiple symmetry-protected Dirac cones. / Ji, Wei-Xiao; Zhang, Bao-Min; Zhang, Shu-Feng; Zhang, Chang-Wen; Ding, Meng; Wang, Pei-Ji; Zhang, Ruiqin.

In: Nanoscale, Vol. 10, No. 28, 28.07.2018, p. 13645-13651.

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review