High domain wall velocities in in-plane magnetized (Ga,Mn)(As,P) layers

Abstract

International audienceField-induced domain wall (DW) propagation was evidenced in unpatterned layers of in-plane magnetized Ga1−xMnxAs1−yPy using Kerr microscopy. Both stationary and precessional regimes were observed, and domain wall velocities of up to 500 m s −1 were measured, of the order of magnitude of those observed on in-plane magnetized metals. Taking advantage of the strain-dependent magneto-crystalline anisotropy in this dilute magnetic semiconductor, both out-of-plane and in-plane anisotropies were adjusted by varying the manganese and phosphorus concentrations. We demonstrate that these anisotropies are a critical parameter to obtain large velocities. These results are interpreted in the framework of the one-dimensional model for domain wall propagation

Spin transfer and spin-orbit torques in in-plane magnetized (Ga,Mn)As tracks

“…After a depinning regime at low fields, the DW velocity increases linearly with field, reaching up to 300 m s −1 on the 2 μm wide C // track. These velocities are typical of those measured under field only on a very similar nonpatterned layer [39], and result from the large DW width of in-plane (Ga,Mn)As. In the C ⊥ tracks, velocities are overall smaller [up to 150 m s −1 , Fig.…”

“…Finally, Cr(10 nm)/Au(200 nm) contacts were thermally evaporated on the sample. Domains were observed with an in-house built longitudinal Kerr microscope, using a λ = 635 nm LED source [39]. A generator was used to apply a continuous or pulsed voltage.…”

“…The measured mobility ratio is therefore a signature of the stationary regime. Also, the precessional regime is expected to be preceded by a large velocity plateau, seen under field only on unpatterned samples [39] and in micromagnetic simulations for C ⊥ and C // tracks [ Fig. 4(b)].…”

Comparison of micromagnetic parameters of the ferromagnetic semiconductors (Ga,Mn)(As,P) and (Ga,Mn)As

“…The possibility of magnetic anisotropy fine tuning by the thermal annealing turns out to be a very favorable property of (Ga,Mn)(As,P) because it enables the preparation of materials with extremely low barriers for magnetization switching [22,23]. Compared to tensile-stained (Ga,Mn)As/(In,Ga)As films, (Ga,Mn)(As,P)/GaAs epilayers show weaker DW pinning, which allows observation of the intrinsic flow regimes of DW propagation [13,15,24].…”

Fast domain wall dynamics in MnAs/GaAs films

“…Details can be found in Ref. [22]. The DW velocity was systematically measured at the site of the largest DW displacement, i.e.…”