  Modulation of magnetic properties through voltage-driven ion motion and redox
processes, i.e., magneto-ionics, is a unique approach to control magnetism with
electric field for low-power memory and spintronic applications. So far,
magneto-ionics has been achieved through direct electrical connections to the
actuated material. Here we evidence that an alternative way to reach such
control exists in a wireless manner. Induced polarization in the conducting
material immersed in the electrolyte, without direct wire contact, promotes
wireless bipolar electrochemistry, an alternative pathway to achieve
voltage-driven control of magnetism based on the same electrochemical processes
involved in direct-contact magneto-ionics. A significant tunability of
magnetization is accomplished for cobalt nitride thin films, including
transitions between paramagnetic and ferromagnetic states. Such effects can be
either volatile or non-volatile depending on the electrochemical cell
configuration. These results represent a fundamental breakthrough that may
inspire future device designs for applications in bioelectronics, catalysis,
neuromorphic computing, or wireless communications.
