Giant Rashba Effect of Polar GeTe, SnTe and PbTe (111) Surfaces: Clarification of the Role of Surface Termination

Narrow gap IVVI semiconductors have attracted tremendous interest due to their intriguing topological crystalline insulator properties with Dirac like surface states as well as the giant Rashba effect in ferroelectric GeTe driven by the large lattice distortion perpendicular to (111). Due to their highly polar nature, however, even the (111) surfaces of paraelectric SnTe and PbTe exhibit a giant Rashba splitting caused by surface band bending due to the cation or anion surface termination. This is also present for GeTe, where accordingly the bulk Rashba bands are superimposed by the Rashba surface bands, making a clear separation of these effects difficult. This proposal aims to clarify this by systematic variation of the surface termination of this series of IVVI surfaces by low temperature submonolayer deposition of Te, Pb, Ge and Sn. Using in situ ARPES we will be able to quantify directly the dependence of the Rashba splitting as a function the surface termination.