Unveiling the complete dispersion of the giant Rashba split surface states of ferroelectric $\alpha$-GeTe(111) by alkali doping

Abstract

$\alpha$-GeTe(111) is a non-centrosymmetric ferroelectric material, for which a strong spin-orbit interaction gives rise to giant Rashba split states in the bulk and at the surface. The detailed dispersions of the surface states inside the bulk band gap remains an open question because they are located in the unoccupied part of the electronic structure, making them inaccessible to static angle-resolved photoemission spectroscopy. We show that this difficulty can be overcome via in-situ potassium doping of the surface, leading to a rigid shift of 80 meV of the surface states into the occupied states. Thus, we resolve in great detail their dispersion and highlight their crossing at the $\bar{\Gamma }$ point, which, in comparison with density functional theory calculations, definitively confirms the Rashba mechanism.

arXiv comment8 pages, 6 figures

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• Triple point fermions in ferroelectric GeTe
• Field-induced ultrafast modulation of Rashba coupling at room temperature in ferroelectric $\alpha$-GeTe(111)
• Reentrant proximity-induced superconductivity for GeTe semimetal
• Current-induced spin and orbital polarization in the ferroelectric Rashba semiconductor GeTe
• Insensitivity of the striped charge-orders in IrTe${}_2$ to alkali surface doping implies their structural origin
• Surface spin polarization in the magnetic response of GeTe Rashba ferroelectric
• Conduction Band Structure and Ultrafast Dynamics of Ferroelectric $\alpha$-GeTe(111)
• Spin-valve effect for spin-polarized surface states in topological semimetals