Individual Domain Wall Resistance in Submicron Ferromagnetic Structures

Danneau, R.; Warin, P.; Attané, J. P.; Petej, I.; Beigné, C.; Fermon, C.; Klein, O.; Marty, A.; Ott, F.; Samson, Y.; Viret, M.

doi:10.1103/physrevlett.88.157201

Cited by 93 publications

(57 citation statements)

References 15 publications

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“…Due to the simplicity of device geometry, it is an open question as to where the DW nucleation starts (possibly at the wire ends or at some local inhomogeneties within the wire) although they are eventually detected within the voltage probes. Similar jumps in the longitudinal resistance have been observed in FePd nanostructure [24]. Multiple vortex walls have also been observed in planar NiFe nanowire of larger width [15].…”

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confidence: 75%

Field-tunable stochasticity in the magnetization reversal of a cylindrical nanomagnet

2010

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The nature of magnetization reversal in an isolated cylindrical nanomagnet has been studied employing time-resolved magnetoresistance measurement. We find that the reversal mode is highly stochastic, occurring either by multimode or single-step switching. Intriguingly, the stochasticity was found to depend on the alignment of the driving magnetic field to the long axis of the nanowires, where predominantly multimode switching gives way to single-step switching behavior as the field direction is rotated from parallel to transverse with respect to the nanowire axis.Traditionally, cylindrical nanomagnets have been of great interest for high density magnetic storage [1], but very recently the dynamics of domain walls (DW) in these systems is also rapidly gaining in importance. A driving factor to this is the absence of "Walker breakdown", with the DWs acting as "massless" particles having zero kinetic energy [2]. However, a generic problem, in both planar or cylindrical nanowires, is the stochasticity associated with the magnetization reversal process. This is manifested in two classes of phenomena: first, the stochasticity associated with diffusive and nondeterministic motion of the DWs in presence of artificial or intrinsic disorder (addressed elsewhere by the same authors [3]); second, the stochasticity related to the nucleation and subsequent propagation of DWs. The latter has been investigated in several planar magnetic films and lithographically patterned nanowires through, for example, size and shape distributions of Barkhausen avalanches, or extraordinary Hall effect etc [4]. Asymmetry in the mode of magnetization switching process on reversal of magnetic field polarity has been investigated using magnetic force microscopy [5], which might as well be related to the stochasticity issue (MFM probes only a fraction of the whole sample). The stochasticity in magnetization reversal in case of cylindrical nanowires, however, is relatively unexplored.Cylindrical magnets have been the classical template for theoretical study of the mode of magnetization reversal and more importantly the angular variation of the nucleation field, albeit in the limit of an infinite and isotropic cylinder [6]. Many experiments on magnetization reversal in nanoscale magnetic systems have looked at the angular dependence assuming an infinite and isotropic cylinder (or strips), although finite size and anisotropy related effects can be crucial in those cases [7][8][9][10][11][12][13][14][15]. Wegrowe et al. could fit their data on angular dependence with the curling mode prediction for an infinite cylinder assuming an activation volume with aspect ratio 2 : 1 (Ref. [16]). Moreover, surface anisotropy or structural defects can also play crucial role and hence cannot be treated within the framework of isotropic magnetization [16]. The principal objective of this article is to explore the effect of angular variation on the stochasticity of magnetization reversal, rather than the variation in switching field (H sw ), where we show that finite...

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confidence: 75%

Field-tunable stochasticity in the magnetization reversal of a cylindrical nanomagnet

2010

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“…A clever device structure fabricated from an epitaxial L1 0 FePd film was used to detect and count individual domain walls by Danneau et al [53] -made possible by the comparatively large DW resistance in this material [237,113,184]. A L-shaped wire was fabricated with the legs running parallel and perpendicular to the stripe domains created during sample growth, which lie along a preferred direction.…”

Section: Mesoscopic Devicesmentioning

confidence: 99%

Spin-polarised currents and magnetic domain walls

Marrows

2005

Advances in Physics

218

163

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Electrical currents flowing in ferromagnetic materials are spinpolarised as a result of the spin-dependent band structure. When the spatial direction of the polarisation changes, in a domain structure, the electrons must somehow accommodate the necessary change in direction of their spin angular momentum as they pass through the wall. Reflection, scattering, and a transfer of angular momentum to the lattice are all possible outcomes, depending on the circumstances. This gives rise to a variety of different physical effects, most importantly a contribution to the electrical resistance caused by the wall, and a motion of the wall driven by the spin-polarised current.Historical and recent research on these topics is reviewed. * Phone: +44(0)113 3433780

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Section: Introductionmentioning

confidence: 98%

“…[4][5][6][7][8][9] Interestingly, the DW resistance turned out in some cases to be negative, 5,6 whereas in other cases to be positive. 4,[7][8][9] Both results have found theoretical explanations. [10][11][12] Levy and Zhang 10 showed that diffuse scattering between electronic states of opposite spin orientation, which occurs in the process of electron transport across the rotating magnetization within a DW, leads to increased resistance.…”

Section: Introductionmentioning

confidence: 98%

Domain-wall magnetoresistance of Co nanowires

et al. 2005

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Using density functional theory implemented within a tight-binding linear muffin-tin orbital method we perform calculations of electronic, magnetic, and transport properties of ferromagnetic free-standing fcc Co wires with diameters up to 1.5 nm. We show that finite-size effects play an important role in these nanowires resulting in oscillatory behavior of electronic charge and the magnetization as a function of the wire thickness, and a nonmonotonic behavior of spin-dependent quantized conductance. We calculate the magnetoresistance ͑MR͒ of a domain wall ͑DW͒ modeled by a spin-spiral region of finite width sandwiched between two semi-infinite Co wire leads. We find that the DW MR decreases very rapidly, on the scale of a few interatomic layers, with the increasing DW width. The largest MR value of about 250% is predicted for an abrupt DW in the monatomic wire. We show that, for some energy values, the density of states and the conductance may be nonzero only in one spin channel, making the MR for the abrupt DW infinitely large. We also demonstrate that for the abrupt DW a large MR may occur due to the hybridization between two spin subbands across the DW interface. We do not find, however, such a behavior at the Fermi energy for the Co wires considered.

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Individual Domain Wall Resistance in Submicron Ferromagnetic Structures

Cited by 93 publications

References 15 publications

Field-tunable stochasticity in the magnetization reversal of a cylindrical nanomagnet

Field-tunable stochasticity in the magnetization reversal of a cylindrical nanomagnet

Spin-polarised currents and magnetic domain walls

Domain-wall magnetoresistance of Co nanowires

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