PChem Seminar - Karl-Heinz Ernst
Event details
| Date | 22.10.2026 |
| Hour | 17:00 › 19:00 |
| Speaker | Karl-Heinz Ernst (EMPA) |
| Location | |
| Category | Conferences - Seminars |
| Event Language | English |
Chirality Meets Magnetism: Spin Selectivity and Molecular Organization
Since Pasteur's discovery of molecular chirality, understanding how molecular handedness couples to its physical environment has remained a fundamental challenge. Of particular interest is its interplay with magnetism, anticipated already by Pierre Curie in 1894, as well as the emergence and propagation of chirality through molecular organization. Here, we explore these connections at surfaces, from the interaction of individual chiral molecules with magnetic substrates and spin-polarized electrons to the collective organization of molecular chirality in extended two-dimensional structures. First, we demonstrate enantioselective adsorption of individual helicene molecules on ferromagnetic cobalt surfaces. Spin- and chirality-resolved scanning tunneling microscopy reveals that left- and right-handed helicenes preferentially adsorb on Co islands with opposite out-of-plane magnetization, establishing a direct correlation between molecular handedness and substrate magnetization. Second, tunneling-conductance measurements through individual enantiomers reveal magnetochiral asymmetries of up to 50%, demonstrating spin-selective electron transport at the single-molecule level and excluding ensemble effects as the sole origin of chirality-induced spin selectivity (CISS). Finally, we report the first observation of aperiodic chiral molecular tiling arising from topological self-assembly on a silver surface, demonstrating how molecular chirality can propagate from individual building blocks into complex collective organization.
Since Pasteur's discovery of molecular chirality, understanding how molecular handedness couples to its physical environment has remained a fundamental challenge. Of particular interest is its interplay with magnetism, anticipated already by Pierre Curie in 1894, as well as the emergence and propagation of chirality through molecular organization. Here, we explore these connections at surfaces, from the interaction of individual chiral molecules with magnetic substrates and spin-polarized electrons to the collective organization of molecular chirality in extended two-dimensional structures. First, we demonstrate enantioselective adsorption of individual helicene molecules on ferromagnetic cobalt surfaces. Spin- and chirality-resolved scanning tunneling microscopy reveals that left- and right-handed helicenes preferentially adsorb on Co islands with opposite out-of-plane magnetization, establishing a direct correlation between molecular handedness and substrate magnetization. Second, tunneling-conductance measurements through individual enantiomers reveal magnetochiral asymmetries of up to 50%, demonstrating spin-selective electron transport at the single-molecule level and excluding ensemble effects as the sole origin of chirality-induced spin selectivity (CISS). Finally, we report the first observation of aperiodic chiral molecular tiling arising from topological self-assembly on a silver surface, demonstrating how molecular chirality can propagate from individual building blocks into complex collective organization.
Practical information
- Informed public
- Free
Organizer
- Sascha Feldmann