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TT: Fachverband Tiefe Temperaturen

TT 32: Focus Session: Spin Phenomena in Chiral Molecular Systems I (joint session O/TT)

TT 32.3: Topical Talk

Tuesday, March 19, 2024, 11:30–12:00, MA 141

Electrical Dipole Moment Governs Spin Polarization in Charge Transport in Single α-helical Peptides Junctions — •Ismael Diez-Perez — Department of Chemistry, Faculty of Natural and Mathematical Science, Kings College London, Britannia House, 21 Swan St

The recent discovery of the CISS (Chirality-induced Spin Selectivity) has many implications for our understanding of biological ET (electron transfer/transport). In this contribution, we are presenting our latest experimental results on spin-dependence ET through single-molecule electrical contacts made of chiral alpha-helical peptide backbones. We synthesize two alpha-helical peptides with homologous sequences of different lengths, 17 and 22 amino acids, and with their two corresponding D- and L- optical isomer. The latter includes the retro-versions of the same sequence, i.e., the same peptide sequence but in an inverted order. To measure spin-dependent single-molecule ET in such structures, we use a magnetic STM break-junction approach we have previously exploited to measure magnetoresistance in single-molecule contacts. The results are explained by an intuitive picture that includes both CISS and interfacial effects. The simple picture has enough flexibility to accommodate the description of the observed differences in magnetoresistance as a function of the magnetization direction of the Ni electrode, the chirality of the peptide, and the peptide dipole orientation on the electrode surface.

Keywords: Single-molecule junctios; Pepetide Chiral sequence; CISS at the single molecule