507 research outputs found
Magnetic characterization and switching of Co nano-rings in current-perpendicular-to-plane configuration
We fabricated Co nano-rings incorporated in the vertical pseudo-spin-valve
nanopillar structures with deep submicron lateral sizes. It is shown that the
current-perpendicular-to-plane giant magnetoresistance can be used to
characterize a very small magnetic nano-ring effectively. Both the onion state
and the flux-closure vortex state are observed. The Co nano-rings can be
switched between the onion states as well as between onion and vortex states
not only by the external field but also by the perpendicularly injected dc
current
Effects of interdot dipole coupling in mesoscopic epitaxial Fe(100) dot arrays
The domain structure and the coercivity of epitaxial Fe(100) circular dot arrays of different diameters and separations have been studied using magnetic force microscopy (MFM) and focused magneto-optical Kerr effect (MOKE). The MFM images of the 1 Β΅m diameter single domain dot arrays show direct evidence of strong interdot dipole coupling when the separation is reduced down to 0.1 Β΅m. The coercivity of the dots is also found to be dependent on the separation, indicating the effect of the interdot dipole coupling on the magnetization reversal process
Megabits secure key rate quantum key distribution
Quantum cryptography (QC) can provide unconditional secure communication
between two authorized parties based on the basic principles of quantum
mechanics. However, imperfect practical conditions limit its transmission
distance and communication speed. Here we implemented the differential phase
shift (DPS) quantum key distribution (QKD) with up-conversion assisted hybrid
photon detector (HPD) and achieved 1.3 M bits per second secure key rate over a
10-km fiber, which is tolerant against the photon number splitting (PNS)
attack, general collective attacks on individual photons, and any other known
sequential unambiguous state discrimination (USD) attacks.Comment: 14 pages, 4 figure
Food, Nutrition, Physical Activity, and the Prevention of Cancer: a Global Perspective
This Report has a number of inter-related general purposes. One is to explore the extent to which food, nutrition, physical activity, and body composition modify the risk of cancer, and to specify which factors are most important. To the extent that environmental factors such as food, nutrition, and physical activity influence the risk of cancer, it is a preventable disease. The Report specifies recommendations based on solid evidence which, when followed, will be expected to reduce the incidence of cancer
The antiphase boundary in half-metallic Heusler alloy Co2Fe(Al,Si) : atomic structure, spin polarization reversal, and domain wall effects
Atomic resolution scanning transmission electron microscopy reveals the presence of an antiphase boundary in the half-metallic Co2Fe(Al,Si) full Heusler alloy. By employing the density functional theory calculations, we show that this defect leads to reversal of the sign of the spin-polarization in the vicinity of the defect. In addition, we show that this defect reduces the strength of the exchange interactions, without changing the ferromagnetic ordering across the boundary. Atomistic spin calculations predict that this effect reduces the width of the magnetic domain wall compared to that in the bulk
Revealing the importance of interfaces for pure spin current transport
Spin transport phenomena underpin an extensive range of spintronic eects. In particular spin transport across interfaces occurs in most device concepts; but is so far poorly understood. As interface properties strongly impact spin transport, one needs to characterize and correlate them to the fabrication method. Here we investigate pure spin current transport across interfaces and connect this with imaging of the interfaces. We study the detection of pure spin currents via the inverse spin Hall eect in Pt and the related spin current absorption by Pt in Py-Cu-Pt lateral spin valves. Depending on the fabrication process to pattern the Cu bridge, we either determine a large (inverse) spin Hall eect signal and low spin absorption by Pt or vice versa. We explain these counter-intuitive results by the fabrication induced varying quality of the Cu/Pt interfaces, which is directly revealed via a special scanning electron microscopy technique for buried interface imaging
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