Disentangling bulk and surface Rashba effects in ferroelectric $\alpha$ -GeTe

Macroscopic ferroelectric order in α-GeTe with its noncentrosymmetric lattice structure leads to a giant Rashba spin splitting in the bulk bands due to strong spin-orbit interaction. Direct measure- ments of the bulk band structure using soft x-ray angle-resolved photoemission (ARPES) reveales the three-dimensional electronic structure with spindle torus shape. By combining high-resolution and spin-resolved ARPES as well as photoemission calculations, the bulk electronic structure is dis- entangled from the two-dimensional surface electronic structure by means of surface capping, which quenches the complex surface electronic structure. This unravels the bulk Rashba-split states in the ferroelectric Rashba α-GeTe(111) semiconductor exhibiting a giant spin-splitting with Rashba parameter αR around 4.2 eV/˚ A, the highest of so-far known materials.

Recommended citation: J. Krempaský, H. Volfová, S. Muff, N. Pilet, G. Landolt, M. Radović, M. Shi, D. Kriegner, V. Holý, J. Braun, H. Ebert, F. Bisti, V. Rogalev, V. Strocov, G. Springholz, J. Minár, J. Dil, "Disentangling bulk and surface Rashba effects in ferroelectric $\alpha$ -GeTe." Physical Review B 20, 205111, (2016).
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