Fig. 1: Skyrmion chirality reversal.
a Schematic representation of the Ta/FeCoB/TaOx trilayer with additional ZrO2 oxide and transparent ITO electrode for gate voltage application. b Schematic cross section of the sample: the top-Ta wedge induces an oxidation gradient at the top interface, leading to c a iDMI sign crossover as directly measured by BLS vs. top-Ta thickness. Error bars of ± 100 MHz on the frequency difference Δf, represented on the right axis, are due to the setup. d, e CIM monitored during 4 s under p-MOKE microscope at the star location shown on b for zero gate voltage and g, h for Vg = + 3.5 V, applied on ITO (the dark rectangular region). The in-plane current density (J ≃ 5 × 109 A/m2) is represented by the white arrow and the out of plane magnetic field is μ0Hext ≃ 80 μT. d, e In the initial state, skyrmions move in the direction of the current (encircled skyrmion moving along the red arrow), indicating CW chirality (D < 0), schematically represented in f. g, h Under the positive gate voltage, an inversion of the skyrmion motion occurs (encircled skyrmion moving along the blue arrow), indicating a CCW chirality (D > 0), as represented in i.
