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| a, Uncompensated magnetization, M, in Mn3−xPtxGa going through a compensation point (M = 0) at x = 0.59 (upper panel): squares are results from theoretical calculations. The line is a guide to eye. Lower panel: Experimental EB field HEB… |
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| Evaluation
of SkX deformation in reciprocal space. a,b, FFT patterns of the
over-focused Lorentz TEM images in Fig. 1c (at 260 K) and Fig. 1d (94 K). c,d, FFT patterns of simulated SkX spin configurations under isotropic and anisotropic DMIs, respectively. Fitting ellipses of the six spots corresponding to magnetic modulation vectors are denoted by dashed curves in a–d. e, SkX deformation parameters a (long axis of the fitting ellipse), b (short axis) and f = 1 − b/a as functions of temperature T (upper abscissa) and estimated strain ε (lower abscissa). f, SkX deformation parameters a, b and f in simulated SkX spin configurations as a function of the degree of introduced DMI anisotropy η = 1 − Dx/Dy. |
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| (a) BLS spectra taken at the Γ-point for the series S1 ADLs with different thicknesses applying a magnetic field μ0H0 = 0.1 T. (b) Calculated SW spatial profiles for the edge (E), the fundamental (F) and the fundamental-localized (Floc) modes. The intensity of the color denotes the amplitude of the excitation, while the red and blue colors indicate opposite phase. |
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| A linear array of periodically spaced and individually controllable skyrmions is introduced as a magnonic crystal. It is numerically demonstrated that skyrmion nucleation and annihilation can be accurately controlled by a nanosecond spin polarized current pulse through a nanocontact. Arranged in a periodic array, such nanocontacts allow the creation of a skyrmion lattice that causes a periodic modulation of the waveguide’s magnetization, which can be dynamically controlled by changing either the strength of an applied external magnetic field or the density of the injected spin current through the nanocontacts. The skyrmion diameter is highly dependent on both the applied field and the injected current. This implies tunability of the lowest band gap as the skyrmion diameter directly affects the strength of the pinning potential. The calculated magnonic spectra thus exhibit tunable allowed frequency bands and forbidden frequency bandgaps analogous to that of conventional magnonic crystals where, in contrast, the periodicity is structurally induced and static. In the dynamic magnetic crystal studied here, it is possible to dynamically turn on and off the artificial periodic structure, which allows switching between full rejection and full transmission of spin waves in the waveguide. These findings should stimulate further research activities on multiple functionalities offered by magnonic crystals based on periodic skyrmion lattices. |
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| MUMAX3 (dots) and OOMMF (lines) solution to standard problem #4a (top graph) and #4b (bottom graph), as well as space-dependent magnetization snapshots when <mx > crosses zero, for fields (a) and (b). All use a 200 × 50 × 1 grid. |
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| We present for the first time an in-depth magnetic characterization of a family of monodisperse cobaltferrite nanoparticles (NPs) with average size covering a broad range of particles sizes (from 4 to 60 nm), synthesized by thermal decomposition of metal−organic precursors. Metal precursors, surfactants, and synthetic parameters were settled in order to fine-tune the particle size, which preserves a narrow particle size distribution. |
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| Applying heat with a specific spatial periodicity to a magnet gives rise to periodically modulated magnetic properties. Stop bands (forbidden frequency gaps) for spin waves (cyan) occur. As a consequence, signal transmission is not allowed. |
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| Information coded into charge or spin currents is converted into magnon currents, processed within the magnonic system and converted back. |
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| Bridging the gap: the ASD link between ab initio methods and micromagnetics simulations. |
