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

Krempaský, J; Volfová, H; Muff, S; Pilet, N; Landolt, G; Radović, M; Shi, M; Kriegner, D; Holý, V; Braun, J; Ebert, H; Bisti, F; Rogalev, V A; Strocov, V N; Springholz, G; Minár, J; Dil, J H (2016). Disentangling bulk and surface Rashba effects in ferroelectric ${\alpha}$-GeTe. Physical Review B, 94(20):205111.

## Abstract

Macroscopic ferroelectric order in ${\alpha}$-GeTe with its noncentrosymmetric lattice structure leads to a giant Rashba spin splitting in the bulk bands due to strong spin-orbit interaction. Direct measurements of the bulk band structure using soft x-ray angle-resolved photoemission (ARPES) reveals 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 disentangled 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 ${\alpha}$-GeTe(111) semiconductor exhibiting a giant spin splitting with Rashba parameter ${\alpha}$R around 4.2 eV Å, the highest of so-far known materials.

## Abstract

Macroscopic ferroelectric order in ${\alpha}$-GeTe with its noncentrosymmetric lattice structure leads to a giant Rashba spin splitting in the bulk bands due to strong spin-orbit interaction. Direct measurements of the bulk band structure using soft x-ray angle-resolved photoemission (ARPES) reveals 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 disentangled 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 ${\alpha}$-GeTe(111) semiconductor exhibiting a giant spin splitting with Rashba parameter ${\alpha}$R around 4.2 eV Å, the highest of so-far known materials.

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## Additional indexing

Item Type: Journal Article, refereed, original work 07 Faculty of Science > Physics Institute 530 Physics Physical Sciences > Electronic, Optical and Magnetic Materials Physical Sciences > Condensed Matter Physics English 2016 09 Jan 2017 09:41 30 Jul 2020 23:39 American Physical Society 2469-9950 Closed https://doi.org/10.1103/PhysRevB.94.205111 : FunderFP7: Grant ID290605: Project TitlePSI-FELLOW - International Fellowship Program on Materials & Matter, Energy & Environment, Human Health & Life-Sciences, and Accelerator Technology