Group-IV tellurides as a route towards all-in-one spin transistors

Simple displacive ferroelectrics GeTe and SnTe have been studied for decades but their intriguing physics based on spin-orbit coupling remained unexplored until few years ago. In particular, they are prototype examples of ferroelectric Rashba semiconductors, a class of materials in which the unique coupling between spin and polar degrees of freedom enables the electrical manipulation of spins. Such a property, combined with a sizable spin Hall effect recently predicted in these materials opens a perspective to integrate different functionalities and construct ferromagnets-free spin devices. Here, we reveal even more intriguing phenomena emerging at the limit of the monolayer. More specifically, we explore the persistent spin texture 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 propose this mechanism as an operation principle of an all-in-one spin transistor, in which spin injection/detection can be accomplished via spin Hall effects.