Efficient Spin-Selective Electron Transport at Low Voltages of Thia-Bridged Triarylamine Hetero[4]helicenes Chemisorbed Monolayer

The Chirality InducedSpin Selectivity (CISS) effect describesthe capability of chiral molecules to act as spin filters discriminatingflowing electrons according to their spin state. Within molecularspintronics, efforts are focused on developing chiral-molecule-basedtechnologies to control the injection and coherence of spin-polarizedcurrents. Herein, for this purpose, we study spin selectivity propertiesof a monolayer of a thioalkyl derivative of a thia-bridged triarylaminehetero[4]helicene chemisorbed on a gold surface. A stacked deviceassembled by embedding a monolayer of these molecules between ferromagneticand diamagnetic electrodes exhibits asymmetric magnetoresistance withinversion of the signal according to the handedness of molecules,in line with the presence of the CISS effect. In addition, magneticallyconductive atomic force microscopy reveals efficient electron spinfiltering even at unusually low potentials. Our results demonstratethat thia[4]heterohelicenes represent key candidates for the developmentof chiral spintronic devices.