| 1. |
- Sluka, Volker, et al.
(författare)
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Emission and propagation of 1D and 2D spin waves with nanoscale wavelengths in anisotropic spin textures
- 2019
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Ingår i: Nature Nanotechnology. - : Springer Nature. - 1748-3387 .- 1748-3395. ; 14:4, s. 328-333
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Tidskriftsartikel (refereegranskat)abstract
- Spin waves offer intriguing perspectives for computing and signal processing, because their damping can be lower than the ohmic losses in conventional complementary metal-oxide-semiconductor (CMOS) circuits. Magnetic domain walls show considerable potential as magnonic waveguides for on-chip control of the spatial extent and propagation of spin waves. However, low-loss guidance of spin waves with nanoscale wavelengths and around angled tracks remains to be shown. Here, we demonstrate spin wave control using natural anisotropic features of magnetic order in an interlayer exchange-coupled ferromagnetic bilayer. We employ scanning transmission X-ray microscopy to image the generation of spin waves and their propagation across distances exceeding multiples of the wavelength. Spin waves propagate in extended planar geometries as well as along straight or curved one-dimensional domain walls. We observe wavelengths between 1 mu m and 150 nm, with excitation frequencies ranging from 250 MHz to 3 GHz. Our results show routes towards the practical implementation of magnonic waveguides in the form of domain walls in future spin wave logic and computational circuits.
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| 2. |
- Ali, Hasan, 1985-, et al.
(författare)
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Quantitative EMCD by use of a double aperture for simultaneous acquisition of EELS
- 2019
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Ingår i: Ultramicroscopy. - : Elsevier BV. - 0304-3991 .- 1879-2723. ; 196, s. 192-196
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Tidskriftsartikel (refereegranskat)abstract
- The weak signal strength in electron magnetic circular dichroism (EMCD) measurements remains one of the main challenges in the quantification of EMCD related EELS spectra. As a consequence, small variations in peak intensity caused by changes of background intervals, choice of method for extraction of signal intensity and equally differences in sample quality can cause strong changes in the EMCD signal. When aiming for high resolution quantitative EMCD, an additional difficulty consists in the fact that the two angular resolved EELS spectra needed to obtain the EMCD signal are taken at two different instances and it cannot be guaranteed that the acquisition conditions for these two spectra are identical. Here, we present an experimental setup where we use a double hole aperture in the transmission electron microscope to obtain the EMCD signal in a single acquisition. This geometry allows for the parallel acquisition of the two electron energy loss spectra (EELS) under exactly the same conditions. We also compare the double aperture acquisition mode with the qE acquisition mode which has been previously used for parallel acquisition of EMCD. We show that the double aperture mode not only offers better signal to noise ratio as compared to qE mode but also allows for much higher acquisition times to significantly improve the signal quality which is crucial for quantitative analysis of the magnetic moments.
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