Acta Chimica Sinica ›› 2023, Vol. 81 ›› Issue (9): 1142-1147.DOI: 10.6023/A23050194 Previous Articles     Next Articles

Special Issue: 庆祝《化学学报》创刊90周年合辑



张凯a,b, 武晓君a,b,*()   

  1. a 中国科学技术大学 化学与材料科学学院 合肥 230026
    b 中国科学技术大学 合肥微尺度物质科学国家研究中心 合肥 230026
  • 投稿日期:2023-05-01 发布日期:2023-06-27
  • 作者简介:
  • 基金资助:
    国家自然科学基金(22073087); 国家自然科学基金(12147105); 国家自然科学基金(22225301)

Room-Temperature Ferromagnetism in Two-Dimensional Janus Titanium Chalcogenides

Kai Zhanga,b, Xiaojun Wua,b()   

  1. a School of Chemistry and Materials Sciences, University of Science and Technology of China, Hefei 230026
    b Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei 230026
  • Received:2023-05-01 Published:2023-06-27
  • Contact: *E-mail:
  • About author:
    Dedicated to the 90th anniversary of Acta Chimica Sinica.
  • Supported by:
    The National Natural Science Foundation of China(22073087); The National Natural Science Foundation of China(12147105); The National Natural Science Foundation of China(22225301)

Design of two-dimensional (2D) ferromagnetic materials with room-temperature magnetism is basic cornerstone for developing nanoscale spintronics. However, the experimental realized room-temperature ferromagnets are very limited and the design of room-temperature ferromagnets based on non-magnetic materials is rarely reported. Motivated by recently synthesized Janus MoSSe monolayer, we have predicted that Janus TiXY (X=S, Se and Te; Y=H and F) monolayers are intrinsic 2D ferromagnetic materials with above room-temperature long-range spin ordering and diverse electronic structures based on systematically first-principles calculations. The six Janus TiXY monolayers tend to adopt T-phase symmetry. The dynamically and thermally stability of lattice are confirmed by phonon spectrum calculations and molecular dynamics simulations. Band structure calculations at HSE06 functional level demonstrate that the monolayer TiTeH and TiTeF are bipolar ferromagnetic semiconductors (BMS) with bandgap of 0.18 and 0.48 eV, respectively. Further, the spin direction-controlled band crossing to band gaped transition and tunable spin splitting at Γ-point are observed in TiTeH monolayer after flipping the spin orientation along from out-of-plane to in-plane direction owing to giant magneto band-structure effect. The TiSH, TiSeH, TeSF, and TiSeF monolayers are half-metallic ferromagnets (HMF) with a large spin gap of 2.67, 1.73, 3.11, and 2.27 eV, respectively. Especially, the estimated Curie temperature (Tc) of TiXH and TiXF based on Monte Carlo simulations are range from 339~401 K and 341~497 K, respectively, which are higher than room-temperature. Similar to bilayer CrI3, we also find a stacking configuration dependent interlayer magnetic coupling ground state in bilayer TiSF. Moreover, taking TiSH and TiSF as prototypes, the intrinsic electronic properties can be maintained after the formation of heterojunctions by applying a protective coating graphene layer. The intrinsic room-temperature ferromagnetism together with diverse electronic structures, making the Janus TiXY monolayer a promising candidate for realistic spintronic applications. Further, constructing Janus monolayers based on nonmagnetic materials opens up new pathway for designing novel 2D ferromagnets.

Key words: Janus monolayer, first-principles, room-temperature ferromagnetism, electronic structures, heterojunction