We present a systematic first-principles study of the spin-orbit torques in the ferromagnetic monolayers ${\mathrm{Fe}}_3{\mathrm{GeTe}}_2$ (FGT) and ${\mathrm{Fe}}_3{\mathrm{GaTe}}_2$ (FGaT). Despite sharing the same crystal structure (point group $D_{3h}$) and predominantly Fe $3d$ spin-polarized bands, the two materials exhibit markedly different current-induced torques. We reveal these differences by computing the full angular dependence of the torkance—the torque per unit applied electric field—using linear-response theory with symmetry-adapted spin-orbit-coupled Wannier functions. FGaT may be viewed as a hole-doped analog of FGT, since Ga contributes one valence electron fewer than Ge. Although the work functions differ by only about 28 meV, the band filling near $K$ and $K^{\prime }$ changes substantially: The density of states at ${\varepsilon }_F$ is reduced by a factor of 3 and its spin polarization reverses from minority in FGT to majority in FGaT. These electronic changes are reflected in the torques resolved by time-reversal parity, sublattice, and momentum. In particular, we identify pronounced hidden torques in FGaT and relate the suppression of its fourth-harmonic Fermi-sea component to the evolution of momentum-space pockets. Finally, we discuss the emergence of such self-torques, which are not captured by the conventional picture of current-induced spin accumulation, within a symmetry-based phenomenological framework. Our results provide microscopic insight into current-induced torques in two-dimensional ferromagnets and offer guidance for defect and van der Waals engineering of layered magnetic materials.

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• Magnetism
• Spin torque
• Spin-orbit coupling
• Spintronics
• Density functional calculations