Thickness dependent wall mobility in thin Permalloy films

Abstract

Domain wall mobility in Permalloy films has been calculated as a function of thickness at 10, 80, and 160 nm which reflects the structure change of Néel, symmetric Bloch and C-shaped (asymmetric Bloch) domain walls. The mobility has been derived from the dynamics of a single nonperiodic domain wall using direct integration of the Landau–Lifshitz–Gilbert equation in a Cartesian lattice. This investigation allows for a detailed examination of spin precession, wall motion and overall magnetization distortion as the wall is moved in the presence of fields ranging from 0.5 to 5 Oe applied in the easy axis direction. At 10-nm-thick films, the mobility of a Néel wall is 30 m/s Oe. Wall motion takes place without noticeable distortion in the magnetization distribution in the vicinity of the Néel wall. For 80 nm-thick films, the mobility of a symmetric Bloch wall is 5 m/s Oe, or 20% less than the theoretical prediction for the mobility of a 180° domain wall model. At dynamic equilibrium, the symmetric Bloch wall has been slightly distorted into a C-shaped wall. For 160 nm-thick films, the mobility of a C-shaped wall is 12 m/s Oe, or 29% less than the theoretical predicted value. Shearing-type magnetization distortion is observed in this composite structure of a Bloch component at the center and Néel caps of opposite chirality at the surfaces.

Physical properties of elongated inorganic nanoparticles

“…(5.13) and (5.14) between the origin and the data point measured at the highest field. These values were much closer to the ones previously observed in films [492] and also to the ones predicted by theory [493]. The results were regarded as a proof that the operational speed of potential spintronic devices involving DW motion in magnetic nanostructures would not be affected by structural confinement.…”

Domain wall dynamics and Barkhausen jumps in thin-film permalloy microstructures

“…Wall mobilities have recently been theoretically studied in permalloy films and stripline structures based on direct integration of the LLG equations. 22,23 The simulated mobilities depend on both the film thickness and stripline width, an apparent manifestation of the effects of geometrical constraints on dynamic DW structure. In addition, detailed studies of DW mobility in nanometer scale wires ͑both experiments and numerical simulations͒ manifest field-dependent mobilities that suggest multiple DW propagation regimes.…”

Magnetic domain wall propagation in nanowires under transverse magnetic fields

“…"Transverse" domain walls have the simplest structure, separating oppositely magnetized domains via simple continuous spin rotation along the length of the wire. 19,20 More recently the magnetic field dependence of domain wall velocity was measured in thinner layers where transverse domain walls are energetically favored. 10,11 Domain walls can overcome any local pinning and propagate along a magnetic nanowire under the influence of either a magnetic field, 12,13 a spin polarized current, [14][15][16] or a combination of the two.…”