Strong current actions on ferrimagnetic domain walls in the creep regime

Abstract

We observe domain-wall (DW) motion in ferrimagnetic TbFe wires with perpendicular anisotropy under combined field and current in the creep regime. The current action on the DW is double: Joule heating and spin-transfer torque. We propose a genuinely robust analysis of velocity, separating thermal effects and spin-transfer torque, quantifying the latter as an equivalent field in the so-called one-dimensional (1D) model. Its efficiency is much larger than in transition-metal ferromagnets above room temperature. The equivalent field reveals the large polarization-to-magnetization ratio in ferrimagnets despite a vanishing M s. The usual 1D DW model is extended to mimic creep and predicts that, in low net magnetization systems, the internal DW structure precesses with currents above a field-independent threshold, leading to two propagation regimes with different mobilities. This is another example of how the internal DW magnetization is relevant in creep. We could not detect experimentally these two regimes, possibly because of the dispersion of the data.

Measurement of the tilt of a moving domain wall shows precession-free dynamics in compensated ferrimagnets

“…After each pulse, a Kerr image is recorded. The DWs move against the electron flow, which is compatible with SOT-driving of chiral Néel DWs with the same relative sign of DMI and SHE as the one found in ferromagnetic Pt/Co 4,30 and which rules out any significant spin-transfer torque 25 . The linearity of the DW displacement with Figure 1.…”

“…In very recent reports the signature of the dynamics at T AC was assigned to a DW mobility peak, under field 17 , 18 , under current by spin–orbit torques (SOT) 19 – 22 , or by spin transfer torque 23 . However, even if this mobility peak is a signature of angular compensation, it is affected by the strong sensitivity of DW propagation to Joule heating and pinning 24 , 25 . Furthermore, none of the latter experiments gives a direct access to the internal DW magnetisation angle that is an intrinsic signature of the magnetisation precession.…”

Deviations from bulk behavior in TbFe(Co) thin films: Interfaces contribution in the biased composition

“…In ferrimagnets, low net magnetization (M S ) promotes the Néel DWs interesting for spin orbit torque DW motion in stacks including heavy metals [6]. This increases the efficiency of current-induced torques [7][8][9], whereas the low magnetization decreases the depinning field [10]. Eventually, at the angular compensation with a nonzero magnetization, field-driven antiferromagnetic spin dynamics is realized in ferrimagnets with a much faster DW propagation [11,12].…”

Voltage-induced inertial domain wall motion in an antiferromagnetic nanowire

“…In the past, researches were concentrated on DW motion in a ferromagnetic (FM) nanowire. In recent years, more attention is paid on special dynamical behaviors of magnetic textures in other magnetic media, such as antiferromagnet (AFM) [19][20][21][22][23], synthetic antiferromagnet (SAF) [24][25][26], ferrimagnet [27][28][29][30], and magnetic frustrate [31][32][33][34]. Typical examples in these cases include ultrahigh velocity and depression of Walker breakdown for coupled DWs in an SAF [24,25], relativisticlike width contraction for an AFM DW, and peculiar AFM DW-magneton interaction [19][20][21]23].…”