  Electrical tunability of spin polarization has been a focus in spintronics.
Here, we report that the trigonal warping (TW) effect, together with spin-orbit
coupling (SOC), can lead to two distinct magnetoelectric effects in
low-dimensional systems. Taking graphene with Rashba SOC as example, we study
the electronic properties and spin-resolved scattering of system. It is found
that the TW effect gives rise to a terraced spin texture in low-energy bands
and can render significant spin polarization in the scattering, both resulting
in an efficient electric control of spin polarization. Our work unveils not
only SOC but also the TW effect is important for low-dimensional spintronics.
