2,009 research outputs found
Surface Roughness Dominated Pinning Mechanism of Magnetic Vortices in Soft Ferromagnetic Films
Although pinning of domain walls in ferromagnets is ubiquitous, the absence
of an appropriate characterization tool has limited the ability to correlate
the physical and magnetic microstructures of ferromagnetic films with specific
pinning mechanisms. Here, we show that the pinning of a magnetic vortex, the
simplest possible domain structure in soft ferromagnets, is strongly correlated
with surface roughness, and we make a quantitative comparison of the pinning
energy and spatial range in films of various thickness. The results demonstrate
that thickness fluctuations on the lateral length scale of the vortex core
diameter, i.e. an effective roughness at a specific length scale, provides the
dominant pinning mechanism. We argue that this mechanism will be important in
virtually any soft ferromagnetic film.Comment: 4 figure
Electrical Detection of Spin Accumulation at a Ferromagnet-Semiconductor Interface
We show that the accumulation of spin-polarized electrons at a forward-biased
Schottky tunnel barrier between Fe and n-GaAs can be detected electrically. The
spin accumulation leads to an additional voltage drop across the barrier that
is suppressed by a small transverse magnetic field, which depolarizes the spins
in the semiconductor. The dependence of the electrical accumulation signal on
magnetic field, bias current, and temperature is in good agreement with the
predictions of a drift-diffusion model for spin-polarized transport.Comment: Submitted to Phys. Rev. Let
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