TY - JOUR

T1 - Occupancy of lattice positions probed by X-ray photoelectron diffraction: A case study of tetradymite topological insulators

AU - Vladimirova, Nadezhda V.

AU - Frolov, Alexander S.

AU - Sánchez-Barriga, Jaime

AU - Clark, Oliver J.

AU - Matsui, Fumihiko

AU - Усачев, Дмитрий Юрьевич

AU - Muntwiler, Matthias

AU - Callaert, Carolien

AU - Hadermann, Joke

AU - Neudachina, Vera S.

AU - Tamm, Marina E.

AU - Yashina, Lada V.

PY - 2023/2/1

Y1 - 2023/2/1

N2 - Occupancy of different structural positions in a crystal lattice often seems to play a key role in material properties. Several experimental techniques have been developed to uncover this issue, all of them being mostly bulk sensitive. However, many materials including topological insulators (TIs), which are among the most intriguing modern materials, are intended to be used in devices as thin films, for which the sublattice occupancy may differ from the bulk. One of the possible approaches to occupancy analysis is X-ray Photoelectron Diffraction (XPD), a structural method in surface science with chemical sensitivity. We applied this method in a case study of Sb2(Te1-xSex)3 mixed crystals, which belong to prototypical TIs. We used high-angle annular dark field (HAADF) scanning transmission electron microscopy (STEM) as a reference method to verify our analysis. We revealed that the XPD data for vacuum cleaved bulk crystals are in excellent agreement with the reference ones. Also, we demonstrate that the anion occupancy near a naturally formed surface can be rather different from that of the bulk. The present results are relevant for a wide range of compositions where the system remains a topological phase, as we ultimately show by probing the transiently occupied topological surface state above the Fermi level by ultrafast photoemission.

AB - Occupancy of different structural positions in a crystal lattice often seems to play a key role in material properties. Several experimental techniques have been developed to uncover this issue, all of them being mostly bulk sensitive. However, many materials including topological insulators (TIs), which are among the most intriguing modern materials, are intended to be used in devices as thin films, for which the sublattice occupancy may differ from the bulk. One of the possible approaches to occupancy analysis is X-ray Photoelectron Diffraction (XPD), a structural method in surface science with chemical sensitivity. We applied this method in a case study of Sb2(Te1-xSex)3 mixed crystals, which belong to prototypical TIs. We used high-angle annular dark field (HAADF) scanning transmission electron microscopy (STEM) as a reference method to verify our analysis. We revealed that the XPD data for vacuum cleaved bulk crystals are in excellent agreement with the reference ones. Also, we demonstrate that the anion occupancy near a naturally formed surface can be rather different from that of the bulk. The present results are relevant for a wide range of compositions where the system remains a topological phase, as we ultimately show by probing the transiently occupied topological surface state above the Fermi level by ultrafast photoemission.

KW - HAADF STEM

KW - Occupancy

KW - Tetradymite

KW - Topological insulators

KW - X-ray photoelectron diffraction

UR - https://www.mendeley.com/catalogue/b3efd9a8-4da0-3b1b-83cb-4cb205589af8/

U2 - 10.1016/j.surfin.2022.102516

DO - 10.1016/j.surfin.2022.102516

M3 - Article

VL - 36

JO - Surfaces and Interfaces

JF - Surfaces and Interfaces

SN - 2468-0230

M1 - 102516

ER -