Direct Observation of Stochastic Domain-Wall Depinning in Magnetic Nanowires

Center for X-ray Optics, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
Physical Review Letters (Impact Factor: 7.51). 05/2009; 102(14):147204. DOI: 10.1103/PhysRevLett.102.147204
Source: PubMed


The stochastic field-driven depinning of a domain wall pinned at a notch in a magnetic nanowire is directly observed using magnetic x-ray microscopy with high lateral resolution down to 15 nm. The depinning-field distribution in Ni80Fe20 nanowires considerably depends on the wire width and the notch depth. The difference in the multiplicity of domain-wall types generated in the vicinity of a notch is responsible for the observed dependence of the stochastic nature of the domain-wall depinning field on the wire width and the notch depth. Thus the random nature of the domain-wall depinning process is controllable by an appropriate design of the nanowire.

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    • "As a possible explanation for the stochastic nature of DW depinning fields, the thermal energy, the edge roughness, and the generation of different types of DW structures can be considered. In our previous work, we have found that the depinning fields are strongly related to the structures of DWs [8] "
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    ABSTRACT: Full-field magnetic transmission x-ray microscopy at high spatial resolution down to 20 nm is used to directly observe field-driven domain wall motion in notch-patterned permalloy nanowires. The depinning process of a domain wall around a notch exhibits a stochastic nature in most nanowires. The stochasticity of the domain wall depinning sensitively depends on the geometry of the nanowire such as the wire thickness, the wire width, and the notch depth. We propose an optimized design of the nanowire for deterministic domain wall depinning field at a notch.
    Journal of Physics Condensed Matter 01/2012; 24(2):024203. DOI:10.1088/0953-8984/24/2/024203 · 2.35 Impact Factor
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    • "shows a typical field distribution for pinning and depinning at the magnetic soft spot A. Note that the pinning field at spot A corresponds to the switching field of the wire without artificial pinning site. The broadness of the depinning field distribution underlines the stochastic nature of the DW depinning process [6]. We do not distinguish between different types of DWs like transverse and vortex walls. "
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    IEEE Transactions on Magnetics 07/2010; 46(6-46):1708 - 1710. DOI:10.1109/TMAG.2010.2042285 · 1.39 Impact Factor
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