Chemical control of the Rashba spin splitting size of α-GeTe(111) surface states by adjusting the potential at the topmost atomic layer

As control of the Rashba spin splitting size is highly desirable for spintronic devices, intensive studies have been performed to vary the splitting size by, for example, applying an electric field or designing novel heterostructures. However, direct observation of Rashba spin splitting size change via spectroscopic measurements has not been done so far. Here, we report results of angle-resolved photoemission studies on ferroelectric alpha-GeTe(111). We observe that the Rashba splitting size of alpha-GeTe(111) surface states is reduced upon dosing with potassium (K) which has a very low electron affinity. Based on density functional theory calculations, we find that the electric potential energy at the topmost atomic layer and the surface potential energy barrier is reduced upon K dosing. This change in the surface potential induces both delocalization of the surface states and reduction of the splitting size. We expect to increase the splitting size by dosing other elements or molecules with high electron affinity.

Automated summary

By conducting angle-resolved photoemission studies on ferroelectric alpha-GeTe(111), it was observed that the Rashba splitting size of surface states is reduced upon potassium (K) doping, due to a decrease in surface potential energy barrier. This change in surface potential leads to delocalization of the surface states and reduction of the splitting size, suggesting the potential to increase the splitting size by doping other elements or molecules with high electron affinity.