Spin Controlled Long Range Interaction

Chiral enantio-separation is a highly needed ability for food, agriculture and pharmaceutical Industries. The traditional methods of separation are based on interactions between two chiral substances, necessarily. For example, a sedimentation reaction of anionic enantiomer with chiral cation, which binds, for spatial reasons, to a certain enantiomer. In recent years, the Chiral Induced Spin Selectivity (CISS) effect was used in devices as a spin filter controling the electron spin transport through the chiral molecules. Using the spin exchange interaction our group have demonstrated the ability to enantio-separate a racemic mixture of a helical thiolated-poly-alanine by reaction with a gold covered ferromagnet under a directed magnetic field. The current work is presenting the ability to achieve generic enantio-selective adsorption even without a covalent bond between the ferromagnet and the analyte molecule. The study also discusses the maximal distance between the ferromagnet and the chiral molecule that this eneatio-selective reaction can be obtained. The observed reaction distance is about 6.3 much longer than estimated from first principle calculation, showing long distance spin coherence. Van Der Peuw Hall Voltage measurements relate the long range interaction through a non-covalent bond with magnetic spin effects. These results open a way to separate enantiomers using enantiomer specific chemistry controlled by the magnetization direction of the substrate.