Biomedical subjects

R Allenspach

Publications and source records attributed to R Allenspach.

At least 19 recordsLinked to original sources

PubMed2005

Direct observation of domain-wall configurations transformed by spin currents.

Direct observations of current-induced domain-wall propagation by spin-polarized scanning electron microscopy are reported. Current pulses move head-to-head as well as tail-to-tail walls in submicrometer Fe20Ni80 wires in the direction of the electron flow, and a decay of the wall velocity with the number of injected current pulses is observed. High-resolution images of the domain walls reveal that the wall spin structure is transformed from a vortex to a transverse configuration with subsequent pulse injections. The change in spin structure is directly correlated with the decay of the velocity.

Journal Article↗

PubMed2002

Direct observation of charge order in an epitaxial NdNiO3 film.

The first direct observation of charge order of Ni(3+delta(')) and Ni(3-delta) by resonant x-ray scattering experiments in an epitaxial film of NdNiO3 is reported. A quantitative value of delta+delta(') = (0.45 +/- 0.04)e was obtained. The temperature dependence of the charge order deviates significantly from those of the magnetic moment and crystallographic structure. This might be an indication of a difference in their fluctuation time scales. These observations are discussed in terms of the temperature-driven metal-insulator transition in the RNiO3 family.

Journal Article↗

PubMed1999

Minimum field strength in precessional magnetization reversal

Ultrafast magnetic field pulses as short as 2 picoseconds are able to reverse the magnetization in thin, in-plane, magnetized cobalt films. The field pulses are applied in the plane of the film, and their direction encompasses all angles with the magnetization. At a right angle to the magnetization, maximum torque is exerted on the spins. In this geometry, a precessional magnetization reversal can be triggered by fields as small as 184 kiloamperes per meter. Applications in future ultrafast magnetic recording schemes can be foreseen.

Journal Article↗

PubMed1996