Near-Electrode Diffusion Dynamics Govern Chirality-Induced Spin Selectivity in an Electrochemical Cell

Chirality-induced spin selectivity (CISS) is a phenomenon resulting from the interaction between chiral molecules and electron spin. One example is chirality-induced magnetoconductance (MC), in which the electrical conduction through a molecule-ferromagnet junction depends on the molecular chirality and the magnetization direction of the ferromagnet. In this study, we investigate the microscopic mechanism of CISS in an electrochemical cell containing a chiral camphorsulfonic acid electrolyte and a ferromagnetic Ni electrode. We find that the MC effect strongly depends on electrode size, which we attribute to a crossover between one-dimensional planar and three-dimensional radial diffusion. Pronounced MC at large electrodes highlights the importance of the one-dimensional planar diffusion regime. This suggests that magnetization reversal modifies exchange coupling between chiral molecules and the ferromagnet, thereby altering the near-electrode concentration gradient rather than the chemical reaction rate per molecule. These findings identify near-electrode diffusion dynamics as a key factor in CISS-related electrochemical responses.