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O: Fachverband Oberflächenphysik
O 50: Spins on Surfaces at the Atomic Scale IV
O 50.2: Talk
Wednesday, March 29, 2023, 10:45–11:00, REC C 213
Spin polarization in polyalanine molecules: the role of coupling, chirality and coordination — •T. N. Ha Nguyen1, L. L.T. Baczewski2, and C. Tegenkamp1 — 1Solid Surface Analysis, Technische Universität Chemnitz, Germany — 2Institute of Physics, Polish Academy of Sciences, Al. Lotnikow, Warszawa, Poland
Propagation of electrons along helical polyalanine-based backbone structures comes along with a robust spin polarization effect. How- ever, studies on a molecular scale are still rare, although this length scale provides direct insight into the role of molecular properties. The self-assembly process and electronic transmission properties of race- mats of right and left handed *-helix polyalanine (DL-PA) molecules from solution on atomically smooth and magnetically switchable Al2O3/Pt/Au/Co/Au substrates was investigated by ambient scan- ning tunneling microscopy and spectroscopy. For various lengths of molecules with and without a cysteine termination, we studied the spin polarization in detail. The phase separation into well-ordered enantiopure hexagonal phases and hetero-dimer structures (DL-PA) allow for the analysis of the spin polarization of PA molecules in different environments. The spin polarization reaches up to 70% for chemisorbed molecules arranged in an hexagonal phase. Our results clearly demonstrate that both the coupling as well as the ordering and coordination are important in order to achieve a high spin-polarization in chiral systems.