51 research outputs found
Vertical current induced domain wall motion in MgO-based magnetic tunnel junction with low current densities
Shifting electrically a magnetic domain wall (DW) by the spin transfer
mechanism is one of the future ways foreseen for the switching of spintronic
memories or registers. The classical geometries where the current is injected
in the plane of the magnetic layers suffer from a poor efficiency of the
intrinsic torques acting on the DWs. A way to circumvent this problem is to use
vertical current injection. In that case, theoretical calculations attribute
the microscopic origin of DW displacements to the out-of-plane (field-like)
spin transfer torque. Here we report experiments in which we controllably
displace a DW in the planar electrode of a magnetic tunnel junction by vertical
current injection. Our measurements confirm the major role of the out-of-plane
spin torque for DW motion, and allow to quantify this term precisely. The
involved current densities are about 100 times smaller than the one commonly
observed with in-plane currents. Step by step resistance switching of the
magnetic tunnel junction opens a new way for the realization of spintronic
memristive devices
Suppression of the spin waves nonreciprocity due to interfacial Dzyaloshinskii Moriya interaction by lateral confinement in magnetic nanostructures
Despite the huge recent interest towards chiral magnetism related to the
interfacial Dzyaloshinskii Moriya interaction (iDMI) in layered systems, there
is a lack of experimental data on the effect of iDMI on the spin waves
eigenmodes of laterally confined nanostructures. Here we exploit Brillouin
Light Scattering (BLS) to analyze the spin wave eigenmodes of non-interacting
circular and elliptical dots, as well as of long stripes, patterned starting
from a Pt(3.4 nm)/CoFeB(0.8 nm) bilayer, with lateral dimensions ranging from
100 nm to 400 nm. Our experimental results, corroborated by micromagnetic
simulations based on the GPU-accelerated MuMax3 software package, provide
evidence for a strong suppression of the frequency asymmetry between
counter-propagating spin waves (corresponding to either Stokes or anti-Stokes
peaks in BLS spectra), when the lateral confinement is reduced from 400 nm to
100 nm, i.e. when it becomes lower than the light wavelength. Such an evolution
reflects the modification of the spin wave character from propagating to
stationary and indicates that the BLS based method of quantifying the i-DMI
strength from the frequency difference of counter propagating spin waves is not
applicable in the case of magnetic elements with lateral dimension below about
400 nm.Comment: Accepted for pubblication by: Physical Review
Colorants in Cheese Manufacture: Production, Chemistry, Interactions, and Regulation
Colored Cheddar cheeses are prepared by adding an aqueous annatto extract (norbixin) to cheese milk; however, a considerable proportion (∼20%) of such colorant is transferred to whey, which can limit the end use applications of whey products. Different geographical regions have adopted various strategies for handling whey derived from colored cheeses production. For example, in the United States, whey products are treated with oxidizing agents such as hydrogen peroxide and benzoyl peroxide to obtain white and colorless spray‐dried products; however, chemical bleaching of whey is prohibited in Europe and China. Fundamental studies have focused on understanding the interactions between colorants molecules and various components of cheese. In addition, the selective delivery of colorants to the cheese curd through approaches such as encapsulated norbixin and microcapsules of bixin or use of alternative colorants, including fat‐soluble/emulsified versions of annatto or beta‐carotene, has been studied. This review provides a critical analysis of pertinent scientific and patent literature pertaining to colorant delivery in cheese and various types of colorant products on the market for cheese manufacture, and also considers interactions between colorant molecules and cheese components; various strategies for elimination of color transfer to whey during cheese manufacture are also discussed
Thickness and power dependence of the spin-pumping effect in Y[subscript 3]Fe[subscript 5]O[subscript 12]Pt heterostructures measured by the inverse spin Hall effect
The dependence of the spin-pumping effect on the yttrium iron garnet (Y[subscript 3]Fe[subscript 5]O[subscript 12], YIG) thickness detected by the inverse spin Hall effect (ISHE) has been investigated quantitatively. Due to the spin-pumping effect driven by the magnetization precession in the ferrimagnetic insulator Y[subscript 3]Fe[subscript 5]O[subscript 12] film a spin-polarized electron current is injected into the Pt layer. This spin current is transformed into electrical charge current by means of the ISHE. An increase of the ISHE voltage with increasing film thickness is observed and compared to the theoretically expected behavior. The effective damping parameter of the YIG/Pt samples is found to be enhanced with decreasing Y[subscript 3]Fe[subscript 5]O[subscript 12] film thickness. The investigated samples exhibit a spin mixing conductance of g[↑↓ over eff] = (3.87 ± 0.21) × 10[superscript 18]m[superscript −2] and a spin Hall angle between θ[subscript ISHE] = 0.013 ± 0.001 and 0.045 ± 0.004 depending on the used spin-diffusion length. Furthermore, the influence of nonlinear effects on the generated voltage and on the Gilbert damping parameter at high excitation powers is revealed. It is shown that for small YIG film thicknesses a broadening of the linewidth due to nonlinear effects at high excitation powers is suppressed because of a lack of nonlinear multimagnon scattering channels. We have found that the variation of the spin-pumping efficiency for thick YIG samples exhibiting pronounced nonlinear effects is much smaller than the nonlinear enhancement of the damping.National Science Foundation (U.S.
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