Ni(NCS)₂ monolayer: a robust bipolar magnetic semiconductor

Searching for experimentally feasible intrinsic two-dimensional ferromagnetic semiconductors is of great significance for applications of nanoscale spintronic devices. Here, based on the first-principles calculations, an Ni(NCS)₂ monolayer was systematically investigated. The results showed that the Ni(NCS)₂ monolayer was a robust bipolar ferromagnetic semiconductor with a moderate bandgap of ∼1.5 eV. Based on the Monte Carlo simulation, its Curie temperature was about 37 K. Interestingly, the Ni(NCS)₂ monolayer remains ferromagnetic ordering when strain and electron doping were applied. However, ferromagnetic-to-antiferromagnetic phase transition occurred when high concentrations of holes were doped. Besides, the Ni(NCS)₂ monolayer is confirmed to be potentially exfoliated from its bulk forms due to its small exfoliated energy. Finally, the Ni(NCS)₂ monolayer's thermodynamic, dynamic, and mechanical stabilities were confirmed by the phonon spectrum calculation, ab initio molecular dynamics simulation and elastic constants calculation, respectively. The results showed that the Ni(NCS)₂ monolayer, as a novel 2D ferromagnetic candidate material of new magnetic molecular framework materials, may have a promising potential for magnetic nanoelectronic devices.