TY - JOUR

T1 - Atomic and Electronic Structure of a Multidomain GeTe Crystal

AU - Frolov, Alexander S.

AU - Sánchez-Barriga, Jaime

AU - Callaert, Carolien

AU - Hadermann, Joke

AU - Fedorov, Alexander V.

AU - Usachov, Dmitry Yu

AU - Chaika, Alexander N.

AU - Walls, Brian C.

AU - Zhussupbekov, Kuanysh

AU - Shvets, Igor V.

AU - Muntwiler, Matthias

AU - Amati, Matteo

AU - Gregoratti, Luca

AU - Varykhalov, Andrei Yu

AU - Rader, Oliver

AU - Yashina, Lada V.

N1 - Funding Information: Financial support from the Russian Science Foundation (RSF) under Grant No. 19-42-06303 and from the Impuls- und Vernetzungsfonds der Helmholtz Gemeinschaft under Grant No. HRSF-0067 (Helmholtz-Russia Joint Research Group) is gratefully acknowledged. J.H. and C.C. acknowledge support through the BOF Grant No. 31445. A.C., B.W., and K.Z. wish to acknowledge an Erasmus+ mobility grant (2017-1-IE02-KA107-000538 and 2017-1-IE02-KA107-000538). A.S.F. acknowledges the travel support of the German–Russian Interdisciplinary Science Center (G-RISC) funded by the German Federal Foreign Office via the German Academic Exchange Service (DAAD). We thank Helmholtz-Zentrum Berlin for granting access to the beamlines and for provision of beamtime at the synchrotron radiation source BESSY-II in Berlin. We acknowledge the Paul Scherrer Institut for provision of synchrotron radiation beamtime at the PEARL beamline of the Swiss Light Source. We gratefully acknowledge Moscow State University for providing access to the Lomonosov supercomputer. Publisher Copyright: © Copyright: Copyright 2020 Elsevier B.V., All rights reserved.

PY - 2020

Y1 - 2020

N2 - Renewed interest in the ferroelectric semiconductor germanium telluride was recently triggered by the direct observation of a giant Rashba effect and a 30-year-old dream about a functional spin field-effect transistor. In this respect, all-electrical control of the spin texture in this material in combination with ferroelectric properties at the nanoscale would create advanced functionalities in spintronics and data information processing. Here, we investigate the atomic and electronic properties of GeTe bulk single crystals and their (111) surfaces. We succeeded in growing crystals possessing solely inversion domains of ∼10 nm thickness parallel to each other. Using HAADF-TEM we observe two types of domain boundaries, one of them being similar in structure to the van der Waals gap in layered materials. This structure is responsible for the formation of surface domains with preferential Te-termination (∼68%) as we determined using photoelectron diffraction and XPS. The lateral dimensions of the surface domains are in the range of ∼10-100 nm, and both Ge- and Te-terminations reveal no reconstruction. Using spin-ARPES we establish an intrinsic quantitative relationship between the spin polarization of pure bulk states and the relative contribution of different terminations, a result that is consistent with a reversal of the spin texture of the bulk Rashba bands for opposite configurations of the ferroelectric polarization within individual nanodomains. Our findings are important for potential applications of ferroelectric Rashba semiconductors in nonvolatile spintronic devices with advanced memory and computing capabilities at the nanoscale.

AB - Renewed interest in the ferroelectric semiconductor germanium telluride was recently triggered by the direct observation of a giant Rashba effect and a 30-year-old dream about a functional spin field-effect transistor. In this respect, all-electrical control of the spin texture in this material in combination with ferroelectric properties at the nanoscale would create advanced functionalities in spintronics and data information processing. Here, we investigate the atomic and electronic properties of GeTe bulk single crystals and their (111) surfaces. We succeeded in growing crystals possessing solely inversion domains of ∼10 nm thickness parallel to each other. Using HAADF-TEM we observe two types of domain boundaries, one of them being similar in structure to the van der Waals gap in layered materials. This structure is responsible for the formation of surface domains with preferential Te-termination (∼68%) as we determined using photoelectron diffraction and XPS. The lateral dimensions of the surface domains are in the range of ∼10-100 nm, and both Ge- and Te-terminations reveal no reconstruction. Using spin-ARPES we establish an intrinsic quantitative relationship between the spin polarization of pure bulk states and the relative contribution of different terminations, a result that is consistent with a reversal of the spin texture of the bulk Rashba bands for opposite configurations of the ferroelectric polarization within individual nanodomains. Our findings are important for potential applications of ferroelectric Rashba semiconductors in nonvolatile spintronic devices with advanced memory and computing capabilities at the nanoscale.

KW - domain walls

KW - electronic structure

KW - ferroelectric domains

KW - germanium telluride

KW - Rashba effect

KW - surface atomic structure

UR - http://www.scopus.com/inward/record.url?scp=85096841477&partnerID=8YFLogxK

U2 - 10.1021/acsnano.0c05851

DO - 10.1021/acsnano.0c05851

M3 - Article

AN - SCOPUS:85096841477

VL - 14

SP - 16576

EP - 16589

JO - ACS Nano

JF - ACS Nano

SN - 1936-0851

IS - 12

ER -