  A new multifunctional 2D material is theoretically predicted based on
systematic ab-initio calculations and model simulations for the honeycomb
lattice of endohedral fullerene W@C28 molecules. It has structural bistability,
ferroelectricity, multiple magnetic phases, and excellent valley characters and
can be easily functionalized by the proximity effect with magnetic isolators
such as MnTiO3. Furthermore, we may also manipulate the valley Hall and spin
transport properties by selectively switch a few W@C28 molecules to the
metastable phase. These findings pave a new way in integrate different
functions in a single 2D material for technological innovations.
