Nonvolatile Ionic Modification of the Dzyaloshinskii-Moriya Interaction

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/HfO2 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 HfO2 layer into the Co and Pt layers and subsequent anchoring. This effect permanently changes the properties of the material, showing that E fields can be used not only for local gating in devices but also as a highly scalable materials design tool for postgrowth tuning of the DMI.