0000000000005394
AUTHOR
K. Richter
Switching by Domain-Wall Automotion in Asymmetric Ferromagnetic Rings
A ring-shaped magnetic logic device offers two vortex states (clockwise and counterclockwise) to encode bits, with relative stability against external magnetic fields. The dynamics of magnetization switching in such structures, though, still need unraveling. The authors present direct experimental visualization of reproducible, robust switching in magnetic rings via domain-wall automotion, which does not require an applied field. Simulations reveal that annihilation of domain walls through automotion always occurs, with the detailed topology of the walls only influencing the dynamics locally, in line with the experimental results.
Automotive domain wall propagation in ferromagnetic rings
Automotive domain wall propagation is a self-propelling motion utilizing the energy stored in a particular energy reservoir of the spin structure to speed up domain wall beyond its equilibrium value given by external driving force and damping. Such a concept of DW motion is of great interest due to recent development of spintronic devices based on domain walls, where automotion could be used to assist or prevent domain wall pinning at low driving fields1-2. In turn, most of studies so far have been devoted to the automotion invoked by DW transformations from metastable to stable states3-4; appearing at sufficiently high magnetic fields strong and enough to trigger domain wall spin structure…
A sphingosine kinase inhibitor combined with temozolomide induces glioblastoma cell death through accumulation of dihydrosphingosine and dihydroceramide, endoplasmic reticulum stress and autophagy.
AbstractGlioblastomas (GBMs) are very aggressive tumors with low chemosensitivity. The DNA-alkylating agent temozolomide (TMZ) is currently the most efficient chemotoxic drug for GBM therapy; however, many patients develop resistance to TMZ. Combining TMZ with another agent could present an improved treatment option if it could overcome TMZ resistance and avoid side effects. Sphingosine kinase inhibitors (SKIs) have emerged as anticancer agents. Sphingosine kinases are often overexpressed in tumors where their activity of phosphorylating sphingosine (Sph) contributes to tumor growth and migration. They control the levels of the pro-apoptotic ceramide (Cer) and Sph and of the pro-survival sp…
Local control of domain wall dynamics in ferromagnetic rings
Ferromagnetic nanorings are of great interest due to prospective applications in memory and logic devices based on domain wall (DW) motion.1-3A key-prerequisite for their realization is a reproducible domain wall spin structure with a well-controllable wall velocity. We have found that DW propagation in magnetic ring is characterized by non-constant vortex DW velocity even below Walker breakdown4 (as opposed to straight wires). Several studies have been devoted to the optimization of ring reversal on a global scale using out-of plane field5 or flux charges emanating from neighboring rings if placed in close proximity6. However, these methods involve DW pinning and vortex nucleation processe…
Local Domain-Wall Velocity Engineering via Tailored Potential Landscapes in Ferromagnetic Rings
One vein of spintronics research seeks to harness propagating magnetic domain walls for information processing. The authors engineer a potential landscape via local variations in a ring geometry, and image the motion of domain walls in rotating magnetic fields to quantify the contribution of the spatially varying potential to wall dynamics. Domain-wall velocity depends on ring width, being highest where the ring is widest, and such a potential thus could be selected to synchronize velocities and enable applications.
Estimation of the spatially distributed surface energy budget for AgriSAR 2006, part I : remote sensing model intercomparison
A number of energy balance models of variable complexity that use remotely sensed boundary conditions for producing spatially distributed maps of surface fluxes have been proposed. Validation typically involves comparing model output to flux tower observations at a handful of sites, and hence there is no way of evaluating the reliability of model output for the remaining pixels comprising a scene. To assess the uncertainty in flux estimation over a remote sensing scene requires one to conduct pixel-by-pixel comparisons of the output. The objective of this paper is to assess whether the simplifications made in a simple model lead to erroneous predictions or deviations from a more complex mod…
Localized domain wall nucleation dynamics in asymmetric ferromagnetic rings revealed by direct time-resolved magnetic imaging
We report time-resolved observations of field-induced domain wall nucleation in asymmetric ferromagnetic rings using single direction field pulses and rotating fields. We show that the asymmetric geometry of a ring allows for controlling the position of nucleation events, when a domain wall is nucleated by a rotating magnetic field. Direct observation by scanning transmission x-ray microscopy (STXM) reveals that the nucleation of domain walls occurs through the creation of transient ripplelike structures. This magnetization state is found to exhibit a surprisingly high reproducibility even at room temperature and we determine the combinations of field strengths and field directions that all…
Skyrmion Hall effect revealed by direct time-resolved X-ray microscopy
Magnetic skyrmions are highly promising candidates for future spintronic applications such as skyrmion racetrack memories and logic devices. They exhibit exotic and complex dynamics governed by topology and are less influenced by defects, such as edge roughness, than conventionally used domain walls. In particular, their finite topological charge leads to a predicted "skyrmion Hall effect", in which current-driven skyrmions acquire a transverse velocity component analogous to charged particles in the conventional Hall effect. Here, we present nanoscale pump-probe imaging that for the first time reveals the real-time dynamics of skyrmions driven by current-induced spin orbit torque (SOT). We…
The effect of adjustable dosing with budesonide/formoterol on health-related quality of life and asthma control compared with fixed dosing
Budesonide/formoterol in a single inhaler is an effective therapy for asthma. We investigated whether adjustable maintenance dosing with budesonide/formoterol could maintain health-related quality of life (HRQL) and asthma control.Asthma patients (n = 4025) received budesonide/formoterol (Symbicort 160/4.5 microg) 2 inhalations twice daily (b.i.d.) for 4 weeks during run-in of this open, multicentre study. Patients were randomised to adjustable dosing (budesonide/formoterol 1 inhalation b.i.d.; stepping up to 2 or 4 inhalations bid for 1 week if asthma worsened) or fixed dosing (budesonide/formoterol 2 inhalations b.i.d.), for 12 weeks. Change in HRQL (standardised Asthma Quality of Life Qu…
Enhanced Magneto-optic Kerr Effect and Magnetic Properties ofCeY2Fe5O12Epitaxial Thin Films
Integrated magneto-optical components require magnetic thin films for tuning of their parameters, and for many applications yttrium iron garnet (YIG) is the material of choice. The authors study high-quality cerium-substituted YIG thin films grown by pulsed laser deposition, which possess tunable magnetic anisotropy and a greatly enhanced magneto-optic Kerr effect, compared to conventional films. This discovery presents new opportunities for engineering tomorrow's magneto-optical and spintronic logic devices.