A mechanism to pin skyrmions in chiral magnets

Liu, Ye-Hua; Li, Youquan

doi:10.1088/0953-8984/25/7/076005

Cited by 79 publications

(103 citation statements)

References 39 publications

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“…Among them are investigations into the current-induced motion of skyrmions and the associated skyrmion Hall effect, 7,13,14 the collective rotation of the skyrmion lattice, 15 and the pinning of skyrmions. 16 In contrast, the dynamics of the internal structure of the skyrmion has not been intensively explored. [17][18][19][20] This is particularly so for the Néel skyrmion whose internal dynamics is much less researched than that of its Bloch counterpart.…”

Section: Introductionmentioning

confidence: 99%

Eigenmodes of Néel skyrmions in ultrathin magnetic films

Zhang

Hou

et al. 2017

AIP Advances

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The static and dynamic states of Néel skyrmions in ultrathin ferromagnetic films with interfacial Dzyaloshinskii-Moriya interaction (DMI) have been micromagnetically simulated as functions of the interfacial DMI strength and applied static magnetic field. Findings reveal that while the breathing, counterclockwise (CCW) and clockwise (CW) rotational eigenmodes exist in the skyrmion lattice (SkL) phase, only the first two modes are present in the isolated skyrmion (ISk) phase. Additionally, the eigenfrequency of the CCW mode is insensitive to the magnetic-field driven SkLISk phase transition, and the inter-skyrmion interaction is largely responsible for exciting the CW mode in the SkL phase. The findings provide physical insight into the dynamics of the phase transition and would be of use to potential skyrmionbased microwave applications.

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Section: Introductionmentioning

confidence: 99%

Eigenmodes of Néel skyrmions in ultrathin magnetic films

Zhang

Hou

et al. 2017

AIP Advances

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“…Secondly, being an insulator, Cu 2 OSeO 3 has magnetic-electric properties [14][15][16][17][18][19][20], which provide a new physical significance in comparison with the B20 crystals. The interconnection between magnetization gradients and electric polarization makes this crystal potentially applicable for data storing devices and spintronics [21][22][23][24]. And thirdly, but not finally, being more complex than the B20 structures (16 magnetic copper atoms in two non-equivalent positions in the unit cell) makes it an interesting object for studying spin textures.…”

Section: Introductionmentioning

confidence: 99%

Microscopic description of twisted magnet Cu2OSeO3

Chizhikov

Дмитриенко

2015

Journal of Magnetism and Magnetic Materials

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a b s t r a c tTwisted structures of chiral cubic ferromagnets MnSi and Cu 2 OSeO 3 can be described both in the frame of the phenomenological Ginzburg-Landau theory and using the microscopical Heisenberg formalism with a chirality arising from the Dzyaloshinskii-Moriya (DM) interaction. Recent progress in quantum firstprincipal methods allows us to calculate interatomic bond parameters of the Heisenberg model, namely isotropic exchange constants J ij and DM vectors D ij , which can be used for simulations of observed magnetic textures and comparison of their calculated characteristics, such as magnetic helix sense and pitch, with an experimental data. In the present work, it is found that unaveraged microscopical details of the spin structures (local canting) have a strong impact on the global twist and can significantly change the helix propagation number. Coefficients and of the phenomenological theory and helix propagation number k /2 = are derived from interatomic parameters J ij and D ij of individual bonds for MnSi and Cu 2 OSeO 3 crystals and similar cubic magnets with almost collinear spins.

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“…The skyrmions can be set into motion by an applied current and are observed to have a very small depinning threshold [38][39][40][41]46,47 , in part because the effectiveness of the Magnus force can be up to ten times stronger than the dissipative force component. The Magnus force introduces a velocity component of the skyrmion that is perpendicular to the direction of an imposed external force, so a skyrmion deflects from or spirals around an attractive pinning site rather than moving directly toward the potential minimum as would occur for systems governed by overdamped dynamics 40,41,[47][48][49][50][51] . Since skyrmions are particle-like objects, many of their dynamical properties can be captured using a point particle model based on a modified Theile's equation that takes into account repulsive skyrmion-skyrmion interactions, the Magnus force, damping, and substrate interactions 47,52 .…”

Section: Introductionmentioning

confidence: 99%

Shapiro steps for skyrmion motion on a washboard potential with longitudinal and transverse ac drives

Reichhardt

2015

Phys. Rev. B

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We numerically study the behavior of two-dimensional skyrmions in the presence of a quasi-onedimensional sinusoidal substrate under the influence of externally applied dc and ac drives. In the overdamped limit, when both dc and ac drives are aligned in the longitudinal direction parallel to the direction of the substrate modulation, the velocity-force curves exhibit classic Shapiro step features when the frequency of the ac drive matches the washboard frequency that is dynamically generated by the motion of the skyrmions over the substrate, similar to previous observations in superconducting vortex systems. In the case of skyrmions, the additional contribution to the skyrmion motion from a non-dissipative Magnus force shifts the location of the locking steps to higher dc drives, and we find that the skyrmions move at an angle with respect to the direction of the dc drive. For a longitudinal dc drive and a perpendicular or transverse ac drive, the overdamped system exhibits no Shapiro steps; however, when a finite Magnus force is present we find pronounced transverse Shapiro steps along with complex two-dimensional periodic orbits of the skyrmions in the phaselocked regimes. Both the longitudinal and transverse ac drives produce locking steps whose widths oscillate with increasing ac drive amplitude. We examine the role of collective skyrmion interactions and find that additional fractional locking steps occur for both longitudinal and transverse ac drives. At higher skyrmion densities, the system undergoes a series of dynamical order-disorder transitions, with the skyrmions forming a moving solid on the phase locking steps and a fluctuating dynamical liquid in regimes between the steps.

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A mechanism to pin skyrmions in chiral magnets

Cited by 79 publications

References 39 publications

Eigenmodes of Néel skyrmions in ultrathin magnetic films

Eigenmodes of Néel skyrmions in ultrathin magnetic films

Microscopic description of twisted magnet Cu2OSeO3

Shapiro steps for skyrmion motion on a washboard potential with longitudinal and transverse ac drives

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