Fig. 3: First-principles calculations of (Fe1 − xCox)4GeTe2.
From: Tunable high-temperature itinerant antiferromagnetism in a van der Waals magnet
a Phase diagram of spin states for (Fe1 − xCox)4GeTe2 with Curie (TC) and Neel (TN) temperatures. Four different spin states in terms of interlayer spin configurations (FM and AFM) and spin orientations (easy-axis and easy-plane) are stabilized depending on doping level and temperature. The unknown magnetic phase is found for x = 0.39 below T = 90 K. The schematic illustration of spin configurations is shown in the inset. b The saturation magnetization Msat (square symbol) and the calculated Msat (cross symbol) as a function of Co doping x. c Doping-dependent total energy difference Δ between the FM and the A-type AFM phases. The FM-to-AFM transition occurs at the critical doping level xc ~ 0.2, in good agreement with experiments. d Calculated interlayer exchange interaction Jinter with different layer distance (d) for x = 0, 0.2, and 0.5. The oscillatory dependence of Jinter(d), captured by the RKKY model, is systematically changed with Co doping. The errors in the experimental data are smaller than the size of the points.
