Temperature-dependent dynamics of stochastic domain-wall depinning in nanowires

Abstract

The temperature dependence of domain-wall depinning in permalloy nanowires is investigated by measuring depinning fields and corresponding depinning times as a function of the external magnetic bias field. Domain walls are pinned at triangular notches in the nanowires and detected noninvasively by Hall micromagnetometry. This technique allows one to acquire depinning-field and depinning-time distributions in the temperature range between 5 and 50 K and thus to determine the stochastics of the depinning process. The results are discussed in terms of the Néel-Brown model for thermally activated magnetization reversal, assuming a single energy barrier to overcome. In general, the cases presented deviate from this description and give a clear indication that a more complex term for the energy landscape of domain-wall depinning at constrictions in nanowires is obligatory.

Intrinsic Nature of Stochastic Domain Wall Pinning Phenomena in Magnetic Nanowire Devices

“…This is of note because behaviours caused by conventional thermal activation typically take place on timescales much too long to be computationally accessible. Indeed, there is some evidence that thermally-activated transitions between DW states may also occur during DW depinning from notches 26 . Furthermore, other modelling 27 and experimental studies 28 have shown that DW pinning at small, roughness-related defect sites, can in-fact be a transient phenomena, with DWs thermally activating over energy barriers to continue their propagation.…”

Generalized analysis of thermally activated domain-wall motion in Co/Pt multilayers

“…The dynamics of magnetic domain walls (DWs) driven by magnetic field [1][2][3][4][5][6][7][8][9][10][11] or electric current is often dictated by interactions with defects.…”

Chirality-Based Vortex Domain-Wall Logic Gates

“…First, DW pinning and depinning has been widely observed to have stochastic character [20,21], a feature that would clearly disrupt the operation of gates. There are two possible causes of such behavior: Walker-breakdowninduced transformations of the DWs during propagation [22,23] and thermally induced effects once they are pinned [24]. In our simulations, we suppress Walker breakdown phenomena by using a high value of the Gilbert damping parameter (α ¼ 0.5).…”