Domain wall motion in Ga: YIG films

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Abstract
The motion of an isolated straight magnetic domain wall established in a Ga : YIG film (Y2.9La0.1Fe3.8Ga1.2O12) by a gradient field of 2.4 kOe/cm and driven by a homogeneous pulse field Ho is studied experimentally. The measurements are performed at different pulse fields in the presence of a static field of 400 Oe in the plane of the film. At low pulse fields (Ho ≤4.1 Oe), the reduced Landau-Lifshitz damping constant and the wall mobility are obtained λ/γ2 = (2.9 ± 1.2) × 10−9 Oe2s and μ=(1.4±0.4)×104 cm/s/Oe, respectively, from the fit with numerical solutions of the Landau-Lifshitz-Slonczewski (LLS) equations of wall motion. At pulse fields Ho >4.1 Oe, it is found that the wall velocity reduces within a few nanoseconds to a constant value of 110 m/s when a ``critical'' velocity of about 400 m/s is reached. The critical velocity is lower than the peak wall velocity from the LLS formalism by a factor of 2.4 and is reached after 15–40 ns of wall motion, depending on the pulse field.