On the Origin of the Chirality-Induced Spin Selectivity in Molecular Junctions and Beyond

When electrons are injected through a chiral molecule, the resulting current may become spin polarized. This effect, known as the chirality-induced spin-selectivity (CISS) effect, has been suggested to emerge due to the interplay between spin–orbit interactions and the chirality within the molecule. However, such explanations require unrealistically large values for the molecular spin–orbit interaction without any physical justification. Put simply, to date, the physical origin of the CISS effect is unknown.Here, we present the “spinterface mechanism” for the CISS effect, based on the interplay between spin–orbit interactions in the electrode, the chirality of the molecule (which induces a solenoid field), and spin-transfer torque at the molecule–electrode interface. The spinterface mechanism has already been shown to allow remarkable fit between theory and data for numerous experiment. We will provide new examples for such fits, further corroborating the mechanism. We will describe a set of experiments which can be used as a “smoking gun” for differentiating this mechanisms from other theoretical explanations. Finally, we will describe a spinterface mechanism for the CISS effect in photo-excited electrons scattered off a layer of chiral molecules.