Crossed-ratchet effects and domain wall geometrical pinning

Marconi, Veronica; Kolton, Alejandro B.; Capitán, José A.; Cuesta, José A.; Pérez-Junquera, Alejandro; Vélez, María; Martín, José Ignacio; Parrondo, Juan M. R.

doi:10.1103/physrevb.83.214403

Cited by 13 publications

(19 citation statements)

References 28 publications

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“…values such as (L, M) = (12, 128), (18,288), (24,512), (36,1152), and (48, 2048), which are commonly used in our calculations.…”

Section: Resultsmentioning

confidence: 99%

“…Within this context, it has been shown experimentally that interfaces of amorphous magnetic Co-Si films can effectively be stabilized [16,17] with the aid of patterned holes that act as non-magnetic vacancies and are placed along a line. Also, a phenomenological model for an elastic interface interacting with obstacles provides a framework for understanding the stabilization effect in terms of the influence of vacancies on the surface tension of the interface [18].…”

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confidence: 99%

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Tricritical wetting in the two-dimensional Ising magnet due to the presence of localized non-magnetic impurities

Trobo

Albano

2016

J. Phys.: Condens. Matter

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Fixed vacancies (non-magnetic impurities) are placed along the centre of Ising strips in order to study the wetting behaviour in this confined system, by means of numerical simulations analysed with the aid of finite size scaling and thermodynamic integration methods. By considering strips of size () where short-range competitive surface fields () act along the M-direction, we observe localization–delocalization transitions of the interface between magnetic domains of different orientation (driven by the corresponding surface fields), which are the precursors of the wetting transitions that occur in the thermodynamic limit. By placing vacancies or equivalently non-magnetic impurities along the centre of the sample, we found that for low vacancy densities the wetting transitions are of second order, while by increasing the concentration of vacancies the transitions become of first order. Second- and first-order lines meet in tricritical wetting points (), where and are the magnitude of the surface field and the temperature, respectively. In the phase diagram, tricritical points shift from the high temperature and weak surface field regime at large vacancy densities to the , limit for low vacancy densities. By comparing the locations of the tricritical points with those corresponding to the case of mobile impurities, we conclude that in order to observe similar effects, in the latter the required density of impurities is much smaller (e.g. by a factor 3–5). Furthermore, a proper density of non magnetic impurities placed along the centre of a strip can effectively pin rather flat magnetic interfaces for suitable values of the competing surface fields and temperature.

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“…values such as (L, M) = (12, 128), (18,288), (24,512), (36,1152), and (48, 2048), which are commonly used in our calculations.…”

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

Tricritical wetting in the two-dimensional Ising magnet due to the presence of localized non-magnetic impurities

Trobo

Albano

2016

J. Phys.: Condens. Matter

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“…In order to design the array geometries we have taken as starting point the model for propagation of elastic interfaces across rectangular arrays of triangular holes used in previous studies, [28] In this framework, the chosen triangle aspect ratio and inter hole distances correspond to a regime that favours flat DW propagation in the forward direction (F mode, propagation field HF ) and kinked DW backward propagation (Bk mode, propagation field H k ), as defined in Fig. 1(d).…”

Section: Accepted Manuscriptmentioning

confidence: 99%

“…[17,26,27] In this case, DWs can be approximated as elastic lines of zero width that can distort throughout their length in response to the 2D asymmetric pinning potential. [28] The motion of these DWs can be quite complex. In particular, the so-called crossed-ratchet effect can be observed: the preferred direction for DW motion can have two opposite directions depending on the applied magnetic field, the geometrical parameters and, more importantly, the shape of the domain wall within the 2D array (flat or kinked).…”

Section: Introductionmentioning

confidence: 99%

2D magnetic domain wall ratchet: The limit of submicrometric holes

et al. 2018

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The study of ratchet and crossed-ratchet effects in magnetic domain wall motion through 2D arrays of asymmetric holes is extended in this article to the submicrometric limit in hole size (small size regime). Therefore, the gap has been closed between the 2D ratchets in the range of tens-of-micrometers (large size regime) and the small size regime 1D ratchets based on nanowires. The combination of Kerr microscopy, X-Ray PhotoEmission Electron Microscopy and micromagnetic simulations has allowed a full magnetic characterisation of both the domain wall (DW) propagation process over the whole array and the local DW morphology and pinning at the holes. It is found that the 2D small size limit is driven by the interplay between DW elasticity and half vortex propagation along hole edges: as hole size becomes comparable to DW width, flat DW propagation modes are favoured over kinked DW propagation due to an enhancement of DW stiffness, and pinned DW segments adopt asymmetric configurations related with Néel DW chirality. Nevertheless, both ratchet and crossed-ratchet effects have been experimentally found, and we propose a new ratchet/ inverted-ratchet effect in the submicrometric range driven by magnetic fields and electrical currents respectively.

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“…In such devices domain walls are moved through what are generally sub-micron ferromagnetic strips wherein the state of the device is related to the physical position of the domain wall. Stable domain wall positioning is often achieved via strong local structural modifications to the strip such as the introduction of notches [12][13][14][15][16] or holes [17][18][19][20] . Such techniques have the advantage of allowing for the definition of the strip and the domain wall pinning sites in a single lithographic step.…”

Section: Introductionmentioning

confidence: 99%

Spatially periodic domain wall pinning potentials: Asymmetric pinning and dipolar biasing

Metaxas

Zermatten

Novak

et al. 2013

Journal of Applied Physics

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Domain wall propagation has been measured in continuous, weakly disordered, quasi-two-dimensional, Isinglike magnetic layers that are subject to spatially periodic domain wall pinning potentials. The potentials are generated non-destructively using the stray magnetic field of ordered arrays of magnetically hard [Co/Pt] m nanoplatelets which are patterned above and are physically separated from the continuous magnetic layer. The effect of the periodic pinning potentials on thermally activated domain wall creep dynamics is shown to be equivalent, at first approximation, to that of a uniform, effective retardation field, H ret , which acts against the applied field, H. We show that H ret depends not only on the array geometry but also on the relative orientation of H and the magnetization of the nanoplatelets. A result of the latter dependence is that wall-mediated hysteresis loops obtained for a set nanoplatelet magnetization exhibit many properties that are normally associated with ferromagnet/antiferromagnet exchange bias systems. These include a switchable bias, coercivity enhancement and domain wall roughness that is dependent on the applied field polarity.

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Crossed-ratchet effects and domain wall geometrical pinning

Cited by 13 publications

References 28 publications

Tricritical wetting in the two-dimensional Ising magnet due to the presence of localized non-magnetic impurities

Tricritical wetting in the two-dimensional Ising magnet due to the presence of localized non-magnetic impurities

2D magnetic domain wall ratchet: The limit of submicrometric holes

Spatially periodic domain wall pinning potentials: Asymmetric pinning and dipolar biasing

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