Study of the velocity plateau of Dzyaloshinskii domain walls

Abstract

We study field-driven domain wall (DW) velocities in asymmetric multilayer stacks with perpendicular magnetic anisotropy and Dzyaloshinskii-Moriya interaction (DMI), both experimentally and by micromagnetic simulations. Using magneto-optical Kerr microscopy under intense and nanoseconds-long fields, we show that DWs in these films propagate at velocities up to hundreds of m/s and that, instead of the expected decrease of velocity after the Walker field, a long plateau with constant velocity is observed, before breakdown. Both the maximum speed and the field extent of the velocity plateau strongly depend on the values of the spontaneous magnetization and the DMI strength, as well as on the magnetic anisotropy. Micromagnetic simulations reproduce these features in sufficiently wide strips, even for perfect samples. A physical model explaining the microscopic origin of the velocity plateau is proposed. I.arXiv:1908.08282v1 [cond-mat.mes-hall]

Dynamics of chiral solitons driven by polarized currents in monoaxial helimagnets

“…The critical current resembles the one appearing in domain walls 54 and is tantamount to the Walker breakdown field [59][60][61] . However, currents beyond the Walker breakdown do not destroy the domain wall, but induce a non-steady precesional motion.…”

Stochastic Processes in Magnetization Reversal Involving Domain-Wall Motion in Magnetic Memory Elements

“…Finally, in rare occasions (≈2% probability, green curves) the midway conductance is crossed multiple times and τ exceeds 7 ns. These events shall be referred to as the "multipleswing" ones that occur when a 180 degree vertical Bloch line [17] appears in the wall while it is slow in the central region of the disc. These interpretations are based on the forthcoming micromagnetic simulations (Fig.…”

“…Alternatively, if choosing on purpose a specific initial tilt for which the wall happens to be maximally slow at the disc center, then the non-uniformity of the tilt can grow and lead to [inset in Fig. 3(c)] the creation of a vertical Bloch line [17]. Coincidently, the DW swings multiple times in the central area with a gyration move before finally passing.…”

A New Type of Domain and Interacting Bloch-lines in a Dzyaloshinskii-Moriya Multilayer Thin Film

“…Bloch-lines (BLs) play a key role in determining the static and dynamic behavior of chiral domain walls and skyrmions in multilayer films with a significant Dzyaloshinskii-Moriya interaction (DMI) [10,11]. Here, we reveal a new spin texture, termed a type-II domain wall pair, that can be stabilized in DMI multilayer thin films through the formation of BLs and apply our previously developed method [5] to quantify complex chiral structures with phase imaging.…”

“…Beyond Fresnel imaging, electron phase retrieval techniques, specifically using the transport-of-intensity equation (TIE), are well-suited to quantitatively map the local magnetic induction with nanometer resolution. Though phase retrieval is generally regarded as qualitative due to the addition of a small nonzero constant, q0, to solve the TIE through Fourier methods and to filter out low frequency noise, with careful image acquisition and analysis, quantitative information can be obtained [6][7][8][9].Bloch-lines (BLs) play a key role in determining the static and dynamic behavior of chiral domain walls and skyrmions in multilayer films with a significant Dzyaloshinskii-Moriya interaction (DMI) [10,11]. Here, we reveal a new spin texture, termed a type-II domain wall pair, that can be stabilized in DMI multilayer thin films through the formation of BLs and apply our previously developed method [5] to quantify complex chiral structures with phase imaging.…”