42 research outputs found
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
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
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
Fabrication of curved-line nanostructures on membranes for transmission electron microscopy investigations of domain walls
We have fabricated curved-line ferromagnetic nanostructures on membranes for transmission electron microscopy investigations of the equilibrium magnetic spin configurations. The magnetic elements were fabricated using electron-beam lithography and a lift-off procedure for pattern transfer. Due to the fragile nature of the membranes, the design of the elements was chosen to ensure that the lift-off was possible without using ultrasound. The elements included three-quarter rings, zig-zag lines and wavy lines with notches resulting in constrictions with widths down to 30 nm. Magnetic configurations were observed using electron holography and Lorentz microscopy. In particular, the details of the spin structure of vortex and transverse walls, and its dependence on the local geometry were obtained. While Lorentz microscopy provided qualitative information about magnetic spin orientations and the positions of domain walls, electron holography gave quantitative high-resolution images of the magnetic induction allowing the direct measurement of the stray field between adjacent domain walls. (c) 2006 Elsevier B.V. All rights reserved
Reactions of Cationic Piano Stool Iron Complexes Containing Phosphorus Ligands with Phosphorus Ylide
On the aromagnetism and anapole moment of anthracene nanocrystals
We report the results of the study of orientation of small anthracene crystals (suspended in liquid) by static and oscillating magnetic fields. They contradict the previous claim that magnetic response of such crystals displays aromagnetism associated with the static toroidal (anapole) moments of the aromatic molecule. The existence of strong aromagnetism in anthracene would be a fundamental result of high importance for the understanding of interactions on the molecular and bio-molecular levels. Instead, our observations are fully consistent with conventional diamagnetism of anthracene molecules