Chirality-Dependent Electron Spin Filtering by Molecular Monolayers of Helicenes

• Published in: The journal of physical chemistry letters Vol. 9; no. 8; pp. 2025 - 2030
• Main Authors: Kettner, Matthias, Maslyuk, Volodymyr V, Nürenberg, Daniel, Seibel, Johannes, Gutierrez, Rafael, Cuniberti, Gianaurelio, Ernst, Karl-Heinz, Zacharias, Helmut
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 19.04.2018
• ISSN: 1948-7185; 1948-7185
• DOI: 10.1021/acs.jpclett.8b00208

The interaction of low-energy photoelectrons with well-ordered monolayers of enantiopure helical heptahelicene molecules adsorbed on metal surfaces leads to a preferential transmission of one longitudinally polarized spin component, which is strongly coupled to the helical sense of the molecules. Heptahelicene, composed of only carbon and hydrogen atoms, exhibits only a single helical turn but shows excess in longitudinal spin polarization of about P Z = 6 to 8% after transmission of initially balanced left- and right-handed spin polarized electrons. Insight into the electronic structure, that is, the projected density of states, and the spin-dependent electron scattering in the helicene molecule is gained by using spin-resolved density functional theory calculations and a model Hamiltonian approach, respectively. Our results support the semiclassical picture of electronic transport along a helical pathway under the influence of spin–orbit coupling induced by the electrostatic molecular potential.