  The control of spin current is pivotal for spintronic applications,
especially for spin-orbit torque devices. Spin Hall effect (SHE) is a prevalent
method to generate spin current. However, it is difficult to manipulate its
spin polarization in nonmagnet. Recently, the discovery of spin current in
ferromagnet offers opportunity to realize the manipulation. In the present
work, the spin current in van der Waals ferromagnet Fe3GeTe2 (FGT) with varying
magnetization is theoretically investigated. It has been observed that the spin
current in FGT presents the nonlinear behavior with respect to magnetization.
The in-plane and out-of-plane spin polarization emerges simultaneously, and the
bilayer FGT can even exhibit arbitrary spin polarization thanks to the reduced
symmetry. More intriguingly, the correlation between anomalous Hall effect
(AHE) and spin anomalous Hall effect (SAHE) has been interpreted from the
aspect of Berry curvature. This work illustrates that the interplay of symmetry
and magnetism can effectively control the magnitude and spin polarization of
the spin current, providing a practical method to realize exotic spin-orbit
torques.
