Magneto‐Ionic Devices With Polymer‐Based Electrolytes

ABSTRACT Magneto‐ionics is a promising technology for unconventional magnetic data storage and energy‐efficient computing. In magneto‐ionic devices, voltage‐triggered ionic processes are exploited to control magnetic properties of an electrode in an electrolyte. Liquid electrolytes typically generate magneto‐ionic effects at lower voltages compared to solid electrolytes, but complicate electronic integration, posing the risk of leakage. Here, we introduce polymer electrolytes for hydroxide‐ and hydrogen‐based magneto‐ionic devices, which enable magneto‐ionic effects at voltages of ∼2 V. For the hydroxide device, a polymer separator soaked in alkaline solution, a gel polymer electrolyte, and an anion exchange membrane are combined with Fe/FeO x nanofilm electrodes. In all three cases, a large voltage‐induced decrease in magnetic coercivity up to 66% is achieved. In the hydrogen device, a proton exchange membrane is utilized to load Co/Pd multilayer electrodes with hydrogen, leading to a coercivity increase. Direct comparison to corresponding liquid magneto‐ionic devices reveals a drastically improved reversibility for the hydrogen polymer device, while the hydroxide polymer devices exhibit an increased energy efficiency by up to a factor of four. Polymer‐based electrolytes could fully replace liquid electrolytes in magneto‐ionics and enable the design of energy‐efficient devices for magnetic data storage and spintronics.