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DS: Fachverband Dünne Schichten

DS 20: Poster

DS 20.48: Poster

Donnerstag, 12. März 2026, 18:30–20:30, P2

Spin-Dependent Transport of CISS in Polyalanine on GMR-like Au/Co/Au Interfaces — •Andreas Cordier¹, Thi Ngoc Ha Nguyen¹, Huu Thoai Ngo¹, Julian Koch¹, Lech Thomas Baczewski², and Christoph Tegenkamp¹ — ¹Technische Universität Chemnitz — ²Polish Academy of Sciences, Warszawa

Chiral molecules enable the investigation of spin-selective transport in a GMR-like Au/Co/Au geometry. We studied 16-mer L-polyalanine adsorbed on such multilayers by LT-UHV-STM and STS. Topography reveals interdigitated molecular arrangements with an intermolecular spacing of -0.9ex~3 nm and reduced long-range order compared to ambient conditions. STS yields a HOMO-LUMO gap of -0.9ex~1.8 eV and an asymmetry of the electronic states, consistent with shifts induced by the intrinsic molecular dipole under the junction electric field. The I-V characteristics show a clear dependence on the Co magnetization orientation, evidencing CISS-driven, spin-dependent transport through the PA layer and allowing an extraction of the molecular CISS-MR.

In magnetic-field-dependent feedback measurements, the tip stabilizes at distinct equilibrium positions depending on the prior Co magnetization direction, producing a robust Δz signal that vanishes on Au/Co/Au reference samples. Using a quantitative model accounting for all resistive elements of the GMR-like stack we relate the measured Δz to the spin-dependent transmission through the molecules. In combination with forthcoming electronic-structure input, this establishes the experimental foundation for a consistent determination of the CISS-induced magnetoresistance in chiral molecules.

Keywords: STM; STS; Polyalanine; CISS effect