208 research outputs found
Imaging magnetic vortex configurations in ferromagnetic nanotubes
We image the remnant magnetization configurations of CoFeB and permalloy
nanotubes (NTs) using x-ray magnetic circular dichroism photo-emission electron
microscopy. The images provide direct evidence for flux-closure configurations,
including a global vortex state, in which magnetization points
circumferentially around the NT axis. Furthermore, micromagnetic simulations
predict and measurements confirm that vortex states can be programmed as the
equilibrium remnant magnetization configurations by reducing the NT aspect
ratio.Comment: 14 pages, 4 figures, link to supplementary informatio
Studies on liver microsomal metabolism and interaction of vinyl chloride and related compounds in relation to possible carcinogenicity
Magnetization reversal of an individual exchange biased permalloy nanotube
We investigate the magnetization reversal mechanism in an individual
permalloy (Py) nanotube (NT) using a hybrid magnetometer consisting of a
nanometer-scale SQUID (nanoSQUID) and a cantilever torque sensor. The Py NT is
affixed to the tip of a Si cantilever and positioned in order to optimally
couple its stray flux into a Nb nanoSQUID. We are thus able to measure both the
NT's volume magnetization by dynamic cantilever magnetometry and its stray flux
using the nanoSQUID. We observe a training effect and temperature dependence in
the magnetic hysteresis, suggesting an exchange bias. We find a low blocking
temperature K, indicating the presence of a thin
antiferromagnetic native oxide, as confirmed by X-ray absorption spectroscopy
on similar samples. Furthermore, we measure changes in the shape of the
magnetic hysteresis as a function of temperature and increased training. These
observations show that the presence of a thin exchange-coupled native oxide
modifies the magnetization reversal process at low temperatures. Complementary
information obtained via cantilever and nanoSQUID magnetometry allows us to
conclude that, in the absence of exchange coupling, this reversal process is
nucleated at the NT's ends and propagates along its length as predicted by
theory.Comment: 8 pages, 4 figure
A combined experimental and theoretical study of Rashba-split surface states on the (√3 x √3) Pb/Ag (111) degrees
Das Paget-von Schroetter-Syndrom: Arbeitsunfall oder Berufskrankheit?
Das Krankheitsbild der "primären\u27; Thrombose der oberen Extremität im Sinne eines "Paget-von Schroetter-Syndrom\u27; (synonym: "An-strengungsthrombose\u27;, "Thrombose par effort\u27;) wird von den gesetzlichen Unfallversicherungsträgern üblicherweise weder als Arbeitsunfall noch als Berufskrankheit anerkannt. Die mehrteilige SATURN*-Studie soll klären, ob und unter welchen Kriterien die Erkrankung als Arbeitsunfall (Dauer der schädigenden Einwirkung bis zu einer Schichtlänge) oder gegebenenfalls als Berufskrankheit nach "Öffnungsklausel" (darüberhinausgehende Einwirkdauer) zu werten ist
Hydrogen Dynamics in Lightweight Tetrahydroborates
The high hydrogen content in complex hydrides such as M[AlH4]x and M[BH4]x (M = Li, Na,K, Mg, Ca) stimulated many research activities to utilize them as hydrogen storage materials. An understanding of the dynamical properties on themolecular level is important to understand and to improve the sorption kinetics. Hydrogen dynamics in complex hydrides comprise long range translational diffusion as well as localized motions like vibrations, librations or rotations. All the different motions are characterized by their specific length- and timescales. Within this review we give an introduction to the physical properties of lightweight complex hydrides and illustrate the huge variety of dynamical phenomena on selected example
Das Paget-von Schroetter-Syndrom: Arbeitsunfall oder Berufskrankheit?
Das Krankheitsbild der "primären'; Thrombose der oberen Extremität im Sinne eines "Paget-von Schroetter-Syndrom'; (synonym: "An-strengungsthrombose';, "Thrombose par effort';) wird von den gesetzlichen Unfallversicherungsträgern üblicherweise weder als Arbeitsunfall noch als Berufskrankheit anerkannt. Die mehrteilige SATURN*-Studie soll klären, ob und unter welchen Kriterien die Erkrankung als Arbeitsunfall (Dauer der schädigenden Einwirkung bis zu einer Schichtlänge) oder gegebenenfalls als Berufskrankheit nach "Öffnungsklausel" (darüberhinausgehende Einwirkdauer) zu werten ist
Bridging the Mid-Infrared-to-Telecom Gap with Silicon Nanophotonic Spectral Translation
Expanding far beyond traditional applications in optical interconnects at
telecommunications wavelengths, the silicon nanophotonic integrated circuit
platform has recently proven its merits for working with mid-infrared (mid-IR)
optical signals in the 2-8 {\mu}m range. Mid-IR integrated optical systems are
capable of addressing applications including industrial process and
environmental monitoring, threat detection, medical diagnostics, and free-space
communication. Rapid progress has led to the demonstration of various silicon
components designed for the on-chip processing of mid-IR signals, including
waveguides, vertical grating couplers, microcavities, and electrooptic
modulators. Even so, a notable obstacle to the continued advancement of
chip-scale systems is imposed by the narrow-bandgap semiconductors, such as
InSb and HgCdTe, traditionally used to convert mid-IR photons to electrical
currents. The cryogenic or multi-stage thermo-electric cooling required to
suppress dark current noise, exponentially dependent upon the ratio Eg/kT, can
limit the development of small, low-power, and low-cost integrated optical
systems for the mid-IR. However, if the mid-IR optical signal could be
spectrally translated to shorter wavelengths, for example within the
near-infrared telecom band, photodetectors using wider bandgap semiconductors
such as InGaAs or Ge could be used to eliminate prohibitive cooling
requirements. Moreover, telecom band detectors typically perform with higher
detectivity and faster response times when compared with their mid-IR
counterparts. Here we address these challenges with a silicon-integrated
approach to spectral translation, by employing efficient four-wave mixing (FWM)
and large optical parametric gain in silicon nanophotonic wires
- …