Influence of Large Magnetic Field Gradients at the Electrochemical Interface

Abstract

AbstractWe investigate how a model single-electron-exchange electrochemical reaction can be influenced by a magnetic field, B, which is a combination of an external applied field and the stray field generated by a Co/Pt multilayer thin film stack with preferred perpendicular magnetization. The Lorentz force, proportional to B, creates gentle bath stirring. The magnetic field gradient force, proportional to grad B, is enhanced by the size reduction provided by nanoscale stripe domain patterns at the magnetic multilayer surface and acts locally at first tens of nm of the electrode/electrolyte interface. Cyclic voltammetry, chronoamperometry and impedance spectroscopy data reveals that such localized magnetic forces impact the electrochemical double layer, however with a change limited to around 7% when turning on and off the magnetic gradient force, with clear indications that the reaction kinetics remain unchanged. Our specific design of the magnetic field forces allows us to differentiate between these two main magnetic force effects and provides better insight into a controversial issue.