Domain wall resistivity in epitaxial thin film microstructures

Kent, Andrew D.; Yu, Jun; Rüdiger, Ulrich; Parkin, S. S. P.

doi:10.1088/0953-8984/13/25/202

Cited by 134 publications

(118 citation statements)

References 59 publications

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“…For a magnetic layer with a well-defined magnetic anisotropy, this domain structure is highly anisotropic and hysteretic. It can also be controlled by engineering the magnetic anisotropy and coercive fields of magnetic media [24,25]. A film of alternating Co and Pt layers with perpendicular magnetic anisotropy (PMA) is the bottom electrode and the source of magnetic fringe fields in many of our devices, but similar results are obtained if the film is isolated from the current path of the device.…”

Section: Magnetic-layer Properties and Characterizationmentioning

confidence: 73%

Magnetic Fringe-Field Control of Electronic Transport in an Organic Film

et al. 2012

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Random, spatially uncorrelated nuclear-hyperfine fields in organic materials dramatically affect electronic transport properties such as electrical conductivity, photoconductivity, and electroluminescence. The influence of these nuclear-hyperfine fields can be overwhelmed by a uniform externally applied magnetic field, even at room temperature where the thermodynamic influences of the resulting nuclear and electronic Zeeman splittings are negligible. As a result, even in applied magnetic fields as small as 10 mT, the kinetics of exciton formation, bipolaron formation, and single-carrier hopping are all modified at room temperature, leading to changes in transport properties in excess of 10% in many materials. Here, we demonstrate a new method of controlling the electrical conductivity of an organic film at room temperature, using the spatially varying magnetic fringe fields of a magnetically unsaturated ferromagnet. (The fringe field is the magnetic field emanating from a ferromagnet, associated with magnetic dipole interactions or, equivalently, the divergence of the magnetization within and at the surfaces of the ferromagnet.) The ferromagnet's fringe fields might act as a substitute for either the applied magnetic field or the inhomogeneous hyperfine field. The size of the effect, the magnetic-field dependence, and hysteretic properties rule out a model where the fringe fields from the ferromagnet provide a local magnetic field that changes the electronic transport properties through the hyperfine field, and show that our effects originate from electrical transport through the inhomogeneous fringe fields coming from the ferromagnet. Surprisingly, these inhomogeneous fringe fields vary over length scales roughly 2 orders of magnitude larger than the hopping length in the organic materials, challenging the fundamental models of magnetoresistance in organic layers which require the correlation length of the inhomogeneous field to correspond roughly to the hopping length.

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Section: Magnetic-layer Properties and Characterizationmentioning

confidence: 73%

Magnetic Fringe-Field Control of Electronic Transport in an Organic Film

et al. 2012

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“…47) However, the patterns in this work is large, and the DW was expected to be thick (e.g., more than 100 nm) as has been reported for continuous Py films. 48,49) The MR effect due to the DW is quite small in such cases, 50) and thus the reduction in resistance is not caused by the DW itself.…”

Section: 3mentioning

confidence: 68%

Development of TEM Holder Generating In-Plane Magnetic Field Used for <i>In-Situ</i> TEM Observation

et al. 2014

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For easy performance of Lorentz microscopy with simultaneous electric measurements, a special specimen holder for transmission electron microscopy (TEM) has been developed that has electromagnets to generate magnetic field and four leads for electric measurements. This TEM holder was evaluated by checking experimental results of permalloy (Ni 0.8 Fe 0.2 ) patterns. Clear observations of domain wall injection into a nanowire and movement of magnetic vortices as well as magnetoresitance during the development of magnetic domains were performed. It appeared possible to apply in-plane magnetic fields along any direction with intensities of less than about 15.9 kA/m (200 Oe).

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“…Magnetic fringe fields induced by a ferromagnet are mainly determined by the magnetic domain structure. For a film with magnetic anisotropy, the domain structure is highly anisotropic and hysteretic and it can be controlled by engineering the magnetic media [29,30]. The strength and the spatial-correlation length of fringe fields from a ferromagnet also depend sensitively on the distance from the ferromanget.…”

Section: Fringe-field-induced Magnetoresistance and Magnetoelectrolummentioning

confidence: 99%