Quantum spin Hall phase in Mo 2 M 2 C 3 O 2 (M = Ti, Zr, Hf) MXenes

• Published in: Journal of materials chemistry. C, Materials for optical and electronic devices Materials for optical and electronic devices, 2016, Vol.4 (48), p.11524-11529
• Main Authors: Si, Chen, You, Jinxuan, Shi, Wujun, Zhou, Jian, Sun, Zhimei
• Format: Article
• Language: English
• ISSN: 2050-7526; 2050-7534
• DOI: 10.1039/C6TC04560J

The quantum spin Hall (QSH) phase is a peculiar physical phenomenon characterized by topologically protected helical edge states, with potential applications in lower-power electronics and spintronics. Here, using first-principles calculations, we predict the QSH phase in Mo 2 M 2 C 3 O 2 (M = Ti, Zr, or Hf), new members with ordered structures in the family of two-dimensional transition metal carbides (MXenes). The QSH phase which is confirmed by the nontrivial Z 2 topological invariant and Dirac edge states arises from a d–d band inversion between the M-d xy,x2−y2 and the Mo-d z2 orbitals and a spin–orbital coupling (SOC)-induced splitting of the M-d xy,x2−y2 orbital at the Γ point. With different M atoms, the QSH gap of Mo 2 M 2 C 3 O 2 ranges from 38 to 152 meV. These findings will broaden the scientific and technological impacts of both QSH materials and MXenes.