Highly Tunable Near-Room Temperature Ferromagnetism in Cr-Doped Layered Td-WTe₂

The discovery of type-II Weyl semimetal states in layered transition metal dichalcogenides Td-WTe₂ indicates great potential for novel electronic, spintronic, and quantum devices. Theoretically, the interaction between the topological states and the magnetic ordered states of Td-WTe₂ enables the modulation of Weyl semimetal states by an external magnetic field. However, currently, ferromagnetism in layered Td-WTe₂ is still elusive and rarely observed. In this research, ferromagnetic order into WTe₂ using magnetic chromium (Cr) doping with a two-step Te flux strategy is introduced. The Curie temperature (T_c) and the ferromagnetic moment are well tuned with a Cr doping concentration. The T_c of the Cr-doped layered Td-WTe₂ could be regulated from 182 to 283 K, which is close to room temperature. The saturation magnetic moment could be changed from 2.26 to 4.20 emu g^–1, which is stronger than most values reported for these materials. Most intriguingly, the Cr-doped layered Td-WTe₂ single crystals still exhibit semimetallic behavior and they possess very large magnetoresistance with obvious Shubnikov de Haas (SdH) quantum oscillations and an anomalous Hall effect. The findings offer feasible ways to induce and tune ferromagnetic orders in layered Td-WTe₂ and thus to control its topological phase with external magnetic fields.