Observation of hidden atomic order at the interface between Fe and topological insulator Bi2Te3

Author(s)

Jaime Sanchez-Barriga, Ilya I. Ogorodnikov, Mikhail V. Kuznetsov, Andrey A. Volykhov, Fumihiko Matsui, Carolien Callaert, Joke Hadermann, Nikolay I. Verbitskiy, Roland J. Koch, Andrei Varykhalov, Oliver Rader, Lada V. Yashina

Abstract

To realize spintronic devices based on topological insulators (TIs), well-defined interfaces between magnetic metals and TIs are required. Here, we characterize atomically precisely the interface between the 3d transition metal Fe and the TI Bi

₂Te

₃ at different stages of its formation. Using photoelectron diffraction and holography, we show that after deposition of up to 3 monolayers Fe on Bi

₂Te

₃ at room temperature, the Fe atoms are ordered at the interface despite the surface disorder revealed by our scanning-tunneling microscopy images. We find that Fe occupies two different sites: a hollow adatom deeply relaxed into the Bi

₂Te

₃ quintuple layers and an interstitial atom between the third (Te) and fourth (Bi) atomic layers. For both sites, our core-level photoemission spectra and density-functional theory calculations demonstrate simultaneous chemical bonding of Fe to both Te and Bi atoms. We further show that upon deposition of Fe up to a thickness of 20 nm, the Fe atoms penetrate deeper into the bulk forming a 2-5 nm interface layer containing FeTe. In addition, excessive Bi is pushed down into the bulk of Bi

₂Te

₃ leading to the formation of septuple layers of Bi

₃Te

₄ within a distance of ∼25 nm from the interface. Controlling the magnetic properties of the complex interface structures revealed by our work will be of critical importance when optimizing the efficiency of spin injection in TI-based devices.

Organisation(s)

Electronic Properties of Materials

External organisation(s)

Helmholtz-Zentrum Berlin für Materialien und Energie, Russian Academy of Sciences, Anuchin Research Institute and Museum of Anthropology, Nara Institute of Science and Technology (NAIST), University of Antwerp, Lawrence Berkeley National Laboratory

Journal

Physical Chemistry Chemical Physics

Volume

19

Pages

30520-30532

No. of pages

13

ISSN

1463-9076

DOI

https://doi.org/10.1039/c7cp04875k

Publication date

12-2017

Peer reviewed

Yes

Austrian Fields of Science 2012

104006 Solid state chemistry, 103018 Materials physics, 103009 Solid state physics, 103020 Surface physics

Keywords

Portal url

https://ucrisportal.univie.ac.at/en/publications/39caf9e0-7047-4d6c-8ca2-97349ab30203