Tunable Magnetic Properties In Van Der Waals Crystals (Fe1-Xcox)(5)Gete2

We report the doping effects of cobalt on van der Waals (vdW) magnet Fe5GeTe2. A series of (Fe1-xCox)(5)GeTe2 (0 <= x <= 0.44) single crystals have been grown, and their structural, magnetic, and transport properties are investigated. For x=0.20, the Curie temperature T-C increases from 276K to 337K. Moreover, the magnetic easy axis is reoriented to the ab-plane from the c-axis in undoped Fe5GeTe2 with largely enhanced magnetic anisotropy. A complex magnetic phase diagram is identified on the higher doping side. The x=0.44 crystal first orders ferromagnetically at T-C=363K and then undergoes an antiferromagnetic (AFM) transition at T-N=335K. Furthermore, magnetic-field-induced spin-flop transitions are observed for the AFM ground state. Our work reveals (Fe1-xCox)(5)GeTe2 as promising candidates for developing spin-related applications and proposes a method to engineer the magnetic properties of the vdW magnet. Published under license by AIP Publishing.