  Manipulating quantum state via electrostatic gating has been intriguing for
many model systems in nanoelectronics. When it comes to the question of
controlling the electron spins, more specifically, the magnetism of a system,
tuning with electric field has been proven to be elusive. Recently, magnetic
layered semiconductors have attracted much attention due to their emerging new
physical phenomena. However, challenges still remain in the demonstration of a
gate controllable magnetism based on them. Here, we show that, via ionic
gating, strong field effect can be observed in few-layered semiconducting
Cr$_{2}$Ge$_{2}$Te$_{6}$ devices. At different gate doping, micro-area Kerr
measurements in the studied devices demonstrate tunable magnetization loops
below the Curie temperature, which is tentatively attributed to the moment
re-balance in the spin-polarized band structure. Our findings of electric-field
controlled magnetism in van der Waals magnets pave the way for potential
applications in new generation magnetic memory storage, sensors, and
spintronics.
