Hyperfine Fields in an Ag/Fe Multilayer Film Investigated with 8Li beta-Detected Nuclear Magnetic Resonance

Low energy $\beta$-detected nuclear magnetic resonance ($\beta$-NMR) was used to investigate the spatial dependence of the hyperfine magnetic fields induced by Fe in the nonmagnetic Ag of an Au(40 \AA)/Ag(200 \AA)/Fe(140 \AA) (001) magnetic multilayer (MML) grown on GaAs. The resonance lineshape in the Ag layer shows dramatic broadening compared to intrinsic Ag. This broadening is attributed to large induced magnetic fields in this layer by the magnetic Fe layer. We find that the induced hyperfine field in the Ag follows a power law decay away from the Ag/Fe interface with power $-1.93(8)$, and a field extrapolated to $0.23(5)$ T at the interface.Comment: 5 pages, 4 figure. To be published in Phys. Rev.

Spin pumping in magnetic trilayer structures with an MgO barrier

We present a study of the interaction mechanisms in magnetic trilayer structures with an MgO barrier grown by molecular beam epitaxy. The interlayer exchange coupling, A ex, is determined using SQUID magnetometry and ferromagnetic resonance (FMR), displaying an unexpected oscillatory behaviour as the thickness, t MgO, is increased from 1 to 4 nm. Transmission electron microscopy confirms the continuity and quality of the tunnelling barrier, eliminating the prospect of exchange arising from direct contact between the two ferromagnetic layers. The Gilbert damping is found to be almost independent of the MgO thickness, suggesting the suppression of spin pumping. The element-specific technique of X-ray detected FMR reveals a small dynamic exchange interaction, acting in concert with the static interaction to induce coupled precession across the multilayer stack. These results highlight the potential of spin pumping and spin transfer torque for device applications in magnetic tunnel junctions relying on commonly used MgO barriers

Erratum to: 36th International Symposium on Intensive Care and Emergency Medicine

[This corrects the article DOI: 10.1186/s13054-016-1208-6.]

Zarządzanie wiedzą w mikro, małych i średnich przedsiębiorstwach. Studia przypadku z powiatu poznańskiego

The publication presents the results of research about the level of knowledge management in micro, small and medium-sized enterprises from Poznan county and the awareness of entrepreneurs of how important it is for the proper functioning of their enterprises. After an initial introduction to knowledge management and division of knowledge into different types, the results of a survey conducted among twenty enterprises are presented. Businesses had the opportunity to select multiple choices in asked questions, but very often added their own comments based on their long-term experience. What is more, in the future research will include more enterprises also from other cities of the Greater Poland province.Niniejsza publikacja przedstawia wyniki badań na temat poziomu zarządzania wiedzą w mikro, małych i średnich przedsiębiorstwach z powiatu poznańskiego oraz świadomości właścicieli firm jak ważną rolę odgrywa ona do poprawnego funkcjonowania ich podmiotów gospodarczych. Po wstępnym wprowadzeniu w tą problematykę oraz podziale wiedzy na różne typy przedstawiono wyniki badania ankietowego przeprowadzonego wśród dwudziestu przedsiębiorstw. Przedsiębiorcy mieli możliwość dokonywania wielokrotnego wyboru w zadawanych pytaniach, niemniej jednak bardzo często dodawali własne komentarze bazując na swoim wieloletnim doświadczeniu. Warto nadmienić, iż w przyszłości badanie obejmie większą ilość przedsiębiorstw, również z innych regionów Województwa Wielkopolskiego

Structural and magnetic properties of NiMnSb/InGaAs/InP(001)

The structural and magnetic properties of NiMnSb films, 5-120 nm thick, grown on InGaAs/InP(001) substrates by molecular-beam epitaxy, were studied by x-ray diffraction, transmission electron microscopy (TEM), and ferromagnetic resonance (FMR) techniques. X-ray diffraction and TEM studies show that the NiMnSb films had the expected half-Heusler structure, and films up to 120 nm were pseudomorphically strained at the interface, greater than the critical thickness for this system, about 70 nm (0.6% mismatch to InP). No interfacial misfit dislocations were detected up to 85 nm, however, relaxation in the surface regions of films thicker than 40 nm was evident in x-ray reciprocal space maps. TEM investigations show that bulk, planar defects are present beginning in the thinnest film (10 nm). Their density remains constant but they gradually increase in size with increasing film thickness. By 40 nm these defects have overlapped to form a quasicontinuous network aligned closely with < 100 > in-plane directions. The associated strain fields and or compositional ordering from these defects introduced a reduction in crystal symmetry that influenced the magnetic properties. The in-plane and perpendicular FMR anisotropies are not well described by bulk and interface contributions. In thick films, the in-plane uniaxial and fourfold anisotropies increased with increasing film thickness. The lattice defects resulted in a large extrinsic magnetic damping caused by two-magnon scattering, an increase in the coersive field with increasing film thickness, and a lower magnetic moment (3.6 Bohr magnetons) compared to the expected value for the bulk crystals (4 Bohr magnetons). (C) 2005 American Institute of Physics

Lateral spin injection and detection through electrodeposited Fe/GaAs contacts

Efforts to achieve efficient injection of spin-polarized electrons into a semiconductor, a key prerequisite for developing electronics that exploit the electron's spin degree of freedom, have so far met with limited success. Here we report experimental studies of lateral spin injection and detection through electrodeposited Fe/GaAs tunnel contacts. We demonstrate spin injection efficiencies two orders of magnitude higher than for state-of-the-art contacts fabricated via ultra-high-vacuum methods, including those with MgO or Al 2O3 tunnel barriers. To account for this enhancement, we propose that an iron oxide layer that forms at the Fe/GaAs interface during electrodeposition, being magnetic acts as a tunnel barrier with a spin-dependent height, presenting quantum spin transport calculations for such systems. This serendipitous discovery of greatly enhanced efficiency of spin injection into GaAs via electrodeposited contacts introduces a promising new direction for the development of practical semiconductor spintronic devices. \ua9 2013 IOP Publishing Ltd.Peer reviewed: YesNRC publication: Ye

Magnetization dynamics in the presence of pure spin currents in magnetic single and double layers in spin ballistic and diffusive regimes

In this paper we study the spin transport by using the spin-pumping effect in epitaxial magnetic single and double layer film structures. For the magnetic single layer sample we show the spin-pumping-induced interface damping increases and saturates with the Au capping layer thickness. In addition magnetic double layerstructures allowed us to investigate both the spin-pump and spin-sink effects. Coupling of pure spin currents to the magnetization via spin-sink effect is studied using time-resolved magneto-optical Kerr effect. These measurements were used to study the propagation of pure spin currents across a Au spacer layer between the two ferromagnets. The propagation of spin momentum density through the Au spacer layer was well described by spin-diffusion equation, which takes into account electron momentum and spin-flip scattering. The spindiffusion theory was integrated into modified Landau-Lifshitz equations accounting in self-consistent manner for spin-pump/sink mechanism and spin momentum density propagation. Good agreement between theory and experimental data was found

Hyperfine fields in a Ag/Fe magnetic multilayer probed with low energy spin polarized Li-8

A beam of low energy Li-8 has been used to probe the hyperfine field distribution in a magnetic multilayer composed of Au(4nm)/Ag(80nm)/Fe(2nm) grown on a GaAs substrate. The beta-NMR frequency spectrum is shown to be a strong function of the implantation energy reflecting the depth dependence of the local hyperfine fields. Correlating the spectra with TRIM.SP implantation profiles allows us to identify signals from the GaAs, Ag and Au layers. The frequency spectrum in Ag is a strong function of energy. A very narrow line, and corresponding distribution of hyperfine fields, is observed when the beam in centered well away front the Fe whereas a much broader distribution is observed when the Li stops close to the Fe. These results demonstrate that low energy beta-NMR can act as a sensitive probe of the induced magnetism in the otherwise non-magnetic Ag spacer layers. (c) 2005 Elsevier B.V. All rights reserved

Development of the (8)Li cross-relaxation technique: Applications in semiconductors and other condensed matter systems

The so-called "cross-relaxation" method is a powerful technique that can be used to provide detailed structural and site information on impurities in condensed matter systems, including semiconductors, In this paper, we report on the progress of its development at the new Li-8 P-detected nuclear magnetic resonance (beta-NMR) facility located in TRIUMF in Vancouver, Canada. We present first measurements using this method on a Cu single crystal and discuss future application for studies of isolated impurities in semiconductors. (C) 2007 Elsevier B.V. All rights reserved