Asymmetric magnetic bubble expansion under in-plane field in Pt/Co/Pt: Effect of interface engineering

Abstract

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Very large domain wall velocities in Pt/Co/GdOx and Pt/Co/Gd trilayers with Dzyaloshinskii-Moriya interaction

“…The symmetric curves measured for Pt/Co/Pt reflect the equivalent dynamics of up/down and down/up DWs, and are in line with the presence in this sample of (non chiral) Bloch walls. Note that deviations from this symmetric trend have been observed by several groups in the low velocity regime [9,10,20].…”

“…In order to visualize the various regimes of DW propagation predicted by the theoretical models, DW speeds were measured as a function of H z . In order to address the DMI strength in the various samples, the DW speeds driven by the H z pulses were measured in the presence of a static in-plane field H x normal to the DW plane [7][8][9][10]. Fig.…”

“…While recent works have studied field-driven DW dynamics in the very low velocity regime [7][8][9][10], few studies have explored the effect of the DMI on the high velocity regime of DW dynamics [11][12][13]. The maximum DW velocity is limited by the breakdown occurring at the socalled Walker field H W , beyond which the DW motion is no longer stationary and its internal structure undergoes continous precession.…”

Energetic molding of chiral magnetic bubbles

“…A minimum in velocity occurs at positive µ o H x for the Up-Down domain wall implying left-handed chirality (Figure 1b) according to the creep law, which is consistent with the sign of DMI measured and calculated elsewhere for Co/Pt interfaces. [16,17,19,26,27] We also note that the curves are highly asymmetric about their minima resulting in a reversal of the preferred growth direction beyond some H x . If the chirality predicted according to the creep law at low fields is correct, this suggests that at large fields, the domain wall where H DM I is anti-parallel to H x displays a greater velocity; something that has not previously been reported.…”

“…[15][16][17] The growth asymmetry of perpendicular chiral magnetic domains in the presence of an externally applied planar magnetic field, H x , was first suggested to originate from the DMI by Kabanov et al [18] and later described in the context of creep DW motion using Co thin films grown on Pt. [16,17,19,20] The creep velocity is given …”