Fig. 4.
DW velocity upon expansion and contraction of domains in TmIG/Pt surrounded by uniformly magnetized TmIG. a vDW of an up–down DW (corresponding to a +m domain in a –m medium) as a function of Jx upon expansion and b contraction. The magnetic field is set to |Hx| = 300 Oe. The inset in a shows an enlarged view of vDW in the flow regime at low current density. c vDW of an up–down DW as a function of Hx upon expansion and d contraction. The current density is fixed at |Jx| = 0.75 × 108 A cm−2 in either case. DWs move faster when Jx is opposite to vDW (red symbols), indicating the presence of a weak DMI favoring left-handed Néel chiral DWs. Dashed lines in either c or d are linear fits to the experimental data assuming the same slope of vDW(Hx) for both polarities of Jx and opposite magnetic field at which vDW crosses zero, which allows evaluating the effective DMI field |HDMI| ~ 12 ± 3 Oe (see ref. 15). The error bars account for the uncertainty in estimating vDW from each measurement