  Spin transistors based on a semiconducting channel attached to ferromagnetic
electrodes suffer from fast spin decay and extremely low spin
injection/detection efficiencies. Here, we propose an alternative all-in-one
spin device whose operation principle relies on electric manipulation of the
spin lifetime in two-dimensional (2D) SnTe, in which the sizable spin Hall
effect eliminates the need for using ferromagnets. In particular, we explore
the persistent spin texture (PST) intrinsically present in the ferroelectric
phase which protects the spin from decoherence and supports extraordinarily
long spin lifetime. Our first-principles calculations followed by symmetry
arguments revealed that such a spin wave mode can be externally detuned by
perpendicular electric field, leading to spin randomization and decrease in
spin lifetime. We further extend our analysis to ultrathin SnTe films and
confirm the emergence of PST as well as a moderate enhancement of intrinsic
spin Hall conductivity. The recent room-temperature observation of the
ferroelectric phase in 2D-SnTe suggests that novel all-electric spintronics
devices are within reach.
