(a) A positive wave packet and a negative packet that both have positive wave vector move in different directions. The amplitude |ψ| is used for plotting. (b) Two positive wave packets with different wave vectors move toward each other too. (c) The normalized average position ⟨ξ⟩ as a function of time for the two cases.
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Reconfigurable magnonic conduits realized in domain walls: a, Spin wave of wavevector k propagating in a domain wall
between two magnetic domains (top view). Spins precess at their given
position (red arrows); electrons do not flow. The white arrows indicate
magnetization vectors, M. b, A magnetic field, H, shifts the spin-wave nanochannel because a domain of magnetization, M, grows at the expense of the other domain. Magnetic volume charges are indicated by plus and minus signs.
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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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| 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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| (a) Simulated resonant modes for an array of 200nm square dots with 100nm interdot separations are plotted as a function of the azimuthal angle ( ) of the bias field. (b) Powerand phase distributions of the simulated modes are shown for four di®erent values of . The color scales are shown at the top right corner of the figure. |
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| We report the time-domain measurements of optically induced precessional dynamics in a series of Co antidot lattices with fixed antidot diameter of 100 nm and with varying lattice constants (S) between 200 and 500 nm. For the sparsest lattice, we observe two bands of precessional modes with a band gap, which increases substantially with the decrease in S down to 300 nm. At S = 200 nm, four distinct bands with significant band gaps appear. The numerically calculated mode profiles show various localized and extended modes with the propagation direction perpendicular to the bias magnetic field. We numerically demonstrate some composite antidot structures with very rich magnonic spectra spreading between 3 and 27 GHz based upon the above experimental observation. |
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| Calculated modal profiles for modes MF, M1, M2, and M3 from Figs. 2 and 3. |
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| Illustration of a transverse DW structure whose m is denoted by the (blue) arrows. |
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| The frequencies of the modes of the isolated elements of different sizes are shown as a function of their ellipticity. In the inset, the mode spectrum of the isolated 100 × 50 × 10 nm3 element is shown. |
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| Measured frequencies (dots) as a function of the SW wave vector along the principal directions of the 1st BZ, for an external magnetic field H=1.0 kOe. The calculated dispersion curves are also reported. |
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| 2D absorption spectra of homogenous width NW arrays. Wire width is 540 nm. Wire separations are (a) s = 810 nm, (b) s = 120 nm, and (c) s = 80 nm. The MOKE results for s = 80 nm are shown in (d). |
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| (a): SEM image of the CPW line and of two nanowires arrays (inset). (b): SEM image of the alternating width nanowire array (w1= 260 nm, w2= 220 nm and edgeto-edge separation g = 60 nm). (c): Full loop 2D FMR absorption spectra for the array. (d): Normalized M-H loop for the array. |
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| (a) The time-resolved Kerr rotation data after a biexponential background subtraction and (b) the corresponding FFT spectra are shown for[Co/Pd]8 films with different Co layer thickness tCo. |
