  The control of the magnetism of ultra-thin ferromagnetic layers using an
electric field rather than a current, if large enough, would lead to many
technologically important applications. To date, while it is usually assumed
the changes in the magnetic anisotropy, leading to such a control, arises from
surface charge doping of the magnetic layer, a number of key experiments cannot
be understood within such a scenario. Much studied is the fact that, for
non-magnetic metals or semi-conductors, a large surface electric field gives
rise to a Rashba spin-orbit coupling which leads to a spin-splitting of the
conduction electrons. For a magnet, this splitting is modified by the exchange
field resulting in a large magnetic anisotropy energy via the
Dzyaloshinskii-Moriya mechanism. This different, yet traditional, path to an
electrically induced anisotropy energy can explain the electric field,
thickness, and material dependence reported in many experiments.
