The possibility of tuning the Dzyaloshinskii-Moriya interaction (DMI) by electric (E)-field gating in ultrathin magnetic materials has opened up new perspectives in terms of controlling the stabilization of chiral spin structures. The most recent efforts have used voltage-induced charge redistribution at the interface between a metal and an oxide to modulate the DMI. This approach is attractive for active devices but tends to be volatile, making it energy-demanding, and it is limited by Coulomb screening in the metal. Here we demonstrate nonvolatile E-field manipulation of the DMI by ionic-liquid gating of Pt/Co/Hf O 2 ultrathin films. The E-field effect on the DMI scales with the E-field exposure time, and we propose that it is linked to the migration of oxygen species from the Hf O 2 layer into the Co and Pt layers and subsequent anchoring. This effect permanently changes the properties of the material, showing that E fields …