Spin Polarization of Polyalanine Molecules in 2D and Dimer-Row Assemblies Adsorbed on Magnetic Substrates: The Role of Coupling, Chirality, and Coordination.

Autor: Ha Nguyen TN; Solid Surface Analysis, Institute of Physics, Chemnitz University of Technology, Reichenhainer Strasse 70, Chemnitz 09126, Germany., Paltiel Y; Department of Applied Physics, Hebrew University of Jerusalem, Jerusalem 91905, Israel.; Center for Nanoscience and Nanotechnology, Hebrew University of Jerusalem, Jerusalem 91905, Israel., Baczewski LT; Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, Warszawa 02-668, Poland., Tegenkamp C; Solid Surface Analysis, Institute of Physics, Chemnitz University of Technology, Reichenhainer Strasse 70, Chemnitz 09126, Germany.
Jazyk: angličtina
Zdroj: ACS applied materials & interfaces [ACS Appl Mater Interfaces] 2023 Apr 05; Vol. 15 (13), pp. 17406-17412. Date of Electronic Publication: 2023 Mar 23.
DOI: 10.1021/acsami.3c01429
Abstrakt: Propagation of electrons along helical molecules adsorbed on surfaces comes along with a robust spin polarization effect called chirality induced spin selectivity CISS. However, experiments on the molecular scale that allow a true correlation of spin effects with the molecular structure are quite rare. Here we have studied the structure of self-assembled chiral molecules and the electronic transmission and spin polarization of the current through the system by means of ambient scanning tunneling microscopy and spectroscopy in heterostructures of various α-helix polyalanine-based molecules (PA) adsorbed on Al 2 O 3 /Pt/Au/Co/Au substrates with perpendicular magnetic anisotropy. We have found a phase separation of the molecules into well-ordered enantiopure 2D hexagonal phases and quasi-1D heterochiral-dimer structures, which allows for the analysis of the spin polarization with almost atomic precision of PA in different phases. The spin polarization reaches up to 75% for chemisorbed molecules arranged in a hexagonal phase. On the contrary, for weakly coupled PA molecules without cysteine anchoring groups in a quasi-1D phase, a spin polarization of around 50% was found. Our results show that both the intermolecular interaction as well as the coupling to the substrate are important and point out that collective effects within the molecules and at the interfaces are required to achieve a high chiral induced spin selectivity.
Databáze: MEDLINE
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