July 2024

Transition-metal dichalcogenides (TMDCs) triggered large interest in condensed matter research since these twodimensional materials exhibit electronic states ascribed to ‘topological invariants’ of the particular crystal structure and facinating properties when prepared in the single-layer limit.
Single-layer TMDCs are crystalline, monatomic metal sheets (of transition metal atoms) sandwiched between two monatomic layers of chalcogens, i.e. the elements sulfur, selenium or tellurium. The research group investigates the ultra-high vacuum growth of these materials on a variety of substrates with the aim to access the specific properties at the atomic scale under ultra-clean conditions.

The kalendar figure shows a result obtained as pre-cursor state of only tellurium atoms interacting with the gold (111) single crystal surface. The scanning tunneling microscope image reveals that the adsorbed tellurium atoms create an ordered superstructure, i.e. the pattern shown in detail here repeats beautifully over several 1000 atomic distances. The unit cell of the structure consists of approximately 35-37 Te atoms which induce a reconstruction of the underlying gold surface. This means that the gold atoms (most likely) have moved away from their original position in the crystal lattice in reaction to the presence of the tellurium atoms.

Recent publications related to this work:

E. Engel, A. Wegerich, A. Raabgrund, M.A. Schneider, Surface Science 748, 122519 (2024)
T. Kißlinger, A. Schewski, A. Raabgrund, H. Loh, L. Hammer, M.A. Schneider, Physical Review B 108, 205412 (2023)
T. Kißlinger, L. Hammer, M.A. Schneider, Physical Review B 104, 155426 (2021)

Research group web site:
https://www.fkp.physik.nat.fau.eu/research-schneider/