Effect of Co or Ni substitution on magnetism in the layered van der Waals ferromagnet Fe₃GaTe₂

We have grown a series of single crystals of two-dimensional van der Waals ferromagnet Fe3GaTe2 substituted with Co or Ni. The large single crystals of (Fe1-xCox)3GaTe2 (0 x 0.55) and (Fe1-xNix)3GaTe2 (0 x 0.46) were characterized with x-ray diffraction, magnetic susceptibility, electrical resistivity, and Hall measurements. Our results show that the magnetic transition temperatures of Fe3GaTe2 are gradually suppressed upon Co or Ni doping. A small amount of Co or Ni doping results in a significant increase of the coercive field. In particular, Co doping tunes the crystals from ferromagnetism to antiferromagnetism and then to the spin-glass state, while Ni doping tunes the crystals from ferromagnetism to spin-glass states. The strong doping-dependent magnetic properties suggest that Fe3GaTe2 has great potential for spintronic applications.