TY  - JOUR
A1  - Okada, Michio
A1  - Rotenberg, Eli
A1  - Kevan, S. D.
A1  - Schäfer, J.
A1  - Ujfalussy, Balazs
A1  - Stocks, G. Malcolm
A1  - Genatempo, B.
A1  - Bruno, E.
A1  - Plummer, E. W.
T1  - Evolution of the electronic structure in \(Mo_{1-x}Re_x\) alloys
JF  - New Journal of Physics
N2  - We report a detailed experimental and theoretical study of the electronic structure of \(Mo_{1-x}Re_x\) random alloys. We have measured electronic band dispersions for clean and hydrogen-covered \(Mo_{1-x}Re_x\) ( 110) with x = 0-0.25 using angle-resolved photoemission spectroscopy. Our results suggest that the bulk and most surface electronic bands shift relative to the Fermi level systematically and approximately rigidly with Re concentration. We distinguish and quantify two contributions to these shifts: a raise of the Fermi energy and an increase of the overall bandwidth. Alloy bands calculated using the first-principles Korringa-Kohn-Rostoker coherent-potential-approximation method accurately predict both of these effects. As derived from the rigid band model, the Fermi energy shift is inversely related to the bulk density of states in this energy region. Using our results, we also characterize an electronic topological transition of the bulk Fermi surface and relate this to bulk transport properties. Finally, we distinguish effects beyond the rigid band approximation: a highly surface-localized state and a composition-dependent impact of the spin-orbit interaction.
KW  - topological transitions
KW  - surface state
KW  - metals
KW  - total energy
KW  - W(110)
KW  - hydrogen
KW  - mo
KW  - superconductivity
KW  - spectra
KW  - coherent potential approximation
Y1  - 2013
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-122993
SN  - 1367-2630
VL  - 15
IS  - 093010
ER  - 
TY  - JOUR
A1  - Stühler, R.
A1  - Kowalewski, A.
A1  - Reis, F.
A1  - Jungblut, D.
A1  - Dominguez, F.
A1  - Scharf, B.
A1  - Li, G.
A1  - Schäfer, J.
A1  - Hankiewicz, E. M.
A1  - Claessen, R.
T1  - Effective lifting of the topological protection of quantum spin Hall edge states by edge coupling
JF  - Nature Communications
N2  - The scientific interest in two-dimensional topological insulators (2D TIs) is currently shifting from a more fundamental perspective to the exploration and design of novel functionalities. Key concepts for the use of 2D TIs in spintronics are based on the topological protection and spin-momentum locking of their helical edge states. In this study we present experimental evidence that topological protection can be (partially) lifted by pairwise coupling of 2D TI edges in close proximity. Using direct wave function mapping via scanning tunneling microscopy/spectroscopy (STM/STS) we compare isolated and coupled topological edges in the 2D TI bismuthene. The latter situation is realized by natural lattice line defects and reveals distinct quasi-particle interference (QPI) patterns, identified as electronic Fabry-Pérot resonator modes. In contrast, free edges show no sign of any single-particle backscattering. These results pave the way for novel device concepts based on active control of topological protection through inter-edge hybridization for, e.g., electronic Fabry-Pérot interferometry.
KW  - topological insulators
KW  - two-dimensional materials
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-300886
VL  - 13
ER  -