63 research outputs found
Spin dependent scattering of a domain-wall of controlled size
Magnetoresistance measurements in the CPP geometry have been performed on
single electrodeposited Co nanowires exchange biased on one side by a sputtered
amorphous GdCo layer. This geometry allows the stabilization of a single domain
wall in the Co wire, the thickness of which can be controlled by an external
magnetic field. Comparing magnetization, resistivity, and magnetoresistance
studies of single Co nanowires, of GdCo layers, and of the coupled system,
gives evidence for an additional contribution to the magnetoresistance when the
domain wall is compressed by a magnetic field. This contribution is interpreted
as the spin dependent scattering within the domain wall when the wall thickness
becomes smaller than the spin diffusion length.Comment: 9 pages, 13 figure
Influence of charged walls and defects on DC resistivity and dielectric relaxations in Cu-Cl boracite
Charged domain walls form spontaneously in Cu-Cl boracite on cooling through
the phase transition. These walls exhibit changed conductivity compared to the
bulk and motion consistent with the existence of negative capacitance. Here, we
present the dielectric permittivity and DC resistivity of bulk Cu-Cl boracite
as a function of temperature (-140 {\deg}C to 150 {\deg}C) and frequency (1 mHz
to 10 MHz). The thermal behaviour of the two observed dielectric relaxations
and the DC resistivity is discussed. We propose that the relaxations can be
explained by the existence of point defects, most likely local complexes
created by a change of valence of Cu and accompanying oxygen vacancies. In
addition, the sudden change in resistivity seen at the phase transition
suggests that conductive domain walls contribute significantly to the
conductivity in the ferroelectric phase.Comment: 9 pages, 4 figure
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