Direct observation of skyrmions with arbitrary helicity in patterned Co/Pt multilayers (2024)

Authorization Required

×

×

• 

  Figure 1

  Skyrmions (a)–(c) and domain walls (d)–(f) with different helicities γ = 0 (Néel); π/4 (canted); π/2 (Bloch), correspondingly. The arrows show the direction of magnetization in the plane of the film; the colors indicate the perpendicular direction of magnetization (red is for up, blue is for down).

  Reuse & Permissions

• 

  Figure 2

  (a) High-resolution cross-section micrograph of multilayer; the distance between atomic planes is ∼0.218 nm; (b) The dark-field plane-view micrograph of Co/Pt multilayer. (c) Selected area diffraction pattern of planar specimen. (d) The geometry of nanomodification: the array of irradiated spots with the reduced anisotropy.

  Reuse & Permissions

• 

  Figure 3

  Simulated magnetization distribution (left column), simulated Fresnel contrast without tilt (column in the center), and simulated Fresnel contrast at 30° tilt along vertical axis (right column) for the Néel skyrmion (first row), for the canted skyrmion (second row), and for the Bloch skyrmion (bottom row). In the insets of (d) and (g) the enlarged red areas are shown to highlight difference between canted and Bloch skyrmions.

  Reuse & Permissions

• 

  Figure 4

  (a) Polar MOKE major and minor hysteresis loops of the initial Co/Pt film with easy-axis perpendicular anisotropy. Circles: magneto-optical measurements; red curve: simulated hysteresis loop; blue curve: minor hysteresis loop; numbers indicate the points where the Fresnel contrast is acquired through in situ magnetization reversal. (b)–(d) Fresnel contrast on micrographs. Figures are acquired at points 1, 2, and 3 of the hysteresis curve, correspondently. The contrasts are obtained at 30° tilt along denoted axis. (e), (f) Simulated magnetization distributions of points 2 and 3 from hysteresis curve, direction denoted by color wheel; black-white colors denote $M_z$ direction. (g), (h) Simulated Fresnel contrast at 30° tilt along denoted axis.

  Reuse & Permissions

• 

  Figure 5

  (a) Typical Fresnel contrast of Néel skyrmions, obtained for the sample with array of the spot with diameter 200 nm, fluence $2.0\times {10}^{15}$ ions per $\mathrm{c}{\mathrm{m}}^2$, tilt 30°; compare Fig.3. (b) Typical Fresnel contrast of Bloch skyrmions (marked by blue circles) and trivial codirectional vortex (marked by red circles). Obtained for the spots with 400-nm diameter, fluence $3.0\times {10}^{15}$ ions per $\mathrm{c}{\mathrm{m}}^2$, tilt 30°; compare Fig.3. (c), (d) Fresnel contrast of canted skyrmions, obtained for the sample with array of the spot with diameter 400 nm and fluence $2.0\times {10}^{15}$ ions per $\mathrm{c}{\mathrm{m}}^2$. Tilting angles 0° and 30°, correspondingly; compare Figs.3 and 3. Same skyrmions on (c) and (d) are marked by yellow circles.

  Reuse & Permissions

• 

  Figure 6

  Diagram of the stability of localized magnetic states. The experimentally observed states are marked by geometrical figures. The boundary lines are schematically drawn for ease of perception.

  Reuse & Permissions

• 

  Figure 7

  Phase diagrams of skyrmion helicity vs diameter and DMI constant for different quality factor 0.64 (a), 0.78 (b), and 0.92 (c). Violet for pure Néel skyrmion, red for Bloch skyrmion. (d) Cross section of (a)–(c) at $D$ = 55 $\mu \mathrm{J}/{\mathrm{m}}^2$; green (solid) line: $K_u=1.1\times {10}^4\mathrm{J}/{\mathrm{m}}^3$; blue (dashed): $K_u=0.9\times {10}^4\mathrm{J}/{\mathrm{m}}^3$; red (dashed-dotted); $K_u=1.3\times {10}^4\mathrm{J}/{\mathrm{m}}^3$.

  Reuse & Permissions

×