Measuring the formation energy barrier of skyrmions in zinc-substituted 
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Wilson, M. N.; Crisanti, M.; A., Barker, Christopher E.; Štefančič, Aleš; White, J. S.; Birch, M. T.; Balakrishnan, G.; Cubitt, R.; Hatton, P. D.

doi:10.1103/physrevb.99.174421

Cited by 28 publications

(29 citation statements)

References 52 publications

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“…The maximal temperature of the skyrmion reads T max = I 0 /b. In our calculations, T max = 50 K. The temperature in our case conforms to the temperature in the experiment 57 . The temperature effect can be included in the LLG equation Eq.…”

Section: Heat Equationsupporting

confidence: 87%

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The optical tweezer of skyrmions

et al. 2020

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In a spin-driven multiferroic system, the magnetoelectric coupling has the form of effective dynamical Dzyaloshinskii–Moriya (DM) interaction. Experimentally, it is confirmed, for instance, for Cu2OSeO3, that the DM interaction has an essential role in the formation of skyrmions, which are topologically protected magnetic structures. Those skyrmions are very robust and can be manipulated through an electric field. The external electric field couples to the spin-driven ferroelectric polarization and the skyrmionic magnetic texture emerged due to the DM interaction. In this work, we demonstrate the effect of optical tweezing. For a particular configuration of the external electric fields it is possible to trap or release the skyrmions in a highly controlled manner. The functionality of the proposed tweezer is visualized by micromagnetic simulations and model analysis.

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Section: Heat Equationsupporting

confidence: 87%

“…5b). This result is supported by the recent experiment 57 showing the robustness of skyrmions in Cu 2 OSeO 3 .…”

Section: Skyrmion Motionsupporting

confidence: 85%

The optical tweezer of skyrmions

et al. 2020

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“…This state is not the energy minimum of the system, however the energy barrier to transition out of it is large enough that at low temperatures no decay of the metastable skyrmion state is observed in experiments; they persist for periods longer than a week [23]. Nevertheless, near the lower boundary of the equilibrium skyrmion state, the lifetime is observed to become very short (seconds) [23,25]. As a result, large cooling rates are required to stabilize a significant population of metastable skyrmions in bulk samples (> 40 K/min for 50% skyrmion population in bulk Cu 2 OSeO 3 ) [26].…”

Section: Introductionmentioning

confidence: 97%

Stability and metastability of skyrmions in thin lamellae ofCu2OSeO3

Wilson

Birch

Štefančič

et al. 2020

Phys. Rev. Research

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We report small angle X-ray scattering (SAXS) measurements of the skyrmion lattice in two 200 nm thick Cu2OSeO3 lamellae aligned with the applied magnetic field parallel to the out of plane [110] or [100] crystallographic directions. Our measurements show that the equilibrium skyrmion phase in both samples is expanded significantly compared to bulk crystals, existing between approximately 30 and 50 K over a wide region of magnetic field. This skyrmion state is elliptically distorted at low fields for the [110] sample, and symmetric for the [100] sample, possibly due to crystalline anisotropy becoming more important at this sample thickness than it is in bulk samples. Furthermore, we find that a metastable skyrmion state can be observed at low temperature by field cooling through the equilibrium skyrmion pocket in both samples. In contrast to the behavior in bulk samples, the volume fraction of metastable skyrmions does not significantly depend on cooling rate. We show that a possible explanation for this is the change in the lowest temperature of the skyrmion state in this lamellae compared to bulk, without requiring different energetics of the skyrmion state. arXiv:1909.07855v1 [cond-mat.str-el]

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“…However, the general structure of the bulk phase diagram is then lost and becomes sample specific and sensitive to the details of the sample preparation. Other approaches for generating extended skyrmion regimes include supercooling through the small skyrmion pocket to create long-lived low-T metastable skyrmion states [3,7,[16][17][18][19][20][21][22] and using targeted chemical substitution [23,24]. In the latter case, inevitable sample disorder makes theoretical treatment challenging, and, in general, such studies do not necessarily provide the desired insights into skyrmion stability mechanisms.…”

Section: Introductionmentioning

confidence: 99%

In situ control of the helical and skyrmion phases in Cu2OSeO3 using high-pressure helium gas up to 5 kbar

et al. 2020

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We report a small-angle neutron scattering study of the helical and skyrmion lattice order in singlecrystal Cu 2 OSeO 3 under quasihydrostatic helium gas pressures up to 5 kbar. By using helium gas as the pressure-transmitting medium (PTM) we ensure pressure application with improved hydrostaticity at cryogenic temperatures compared with previous reports where liquid PTMs were used. For 5-kbar He gas pressure we observe modest changes of the ambient pressure phase diagram; the critical temperature T c changes by +2.8(2)%, while in the low-T limit the helical propagation vector |q| changes by −0.5(2)%, the lower critical field H c1 changes by +2.5(1.0)%, and the upper critical field H c2 remains unchanged within uncertainty. The skyrmion phase also changes little under pressure; its largest T extent varies from T c − 2.5(5) K at ambient pressure to T c − 3.0(5) K at 5 kbar, and its location in the phase diagram follows the pressure-driven shift of T c. The weak pressure dependences of the critical magnetic fields and skyrmion phase contrast strongly with much stronger pressure-driven changes reported from previous quasihydrostatic pressure studies. Taking into account the present results and those of other uniaxial pressure data, we suggest that the results of previous quasihydrostatic pressure studies were influenced by inadvertent directional stress pressure components. Overall, our study represents a high-pressure study of the chiral magnetism in Cu 2 OSeO 3 under the most hydrostatic high-pressure conditions to date and serves also as a salient reminder of the sensitivity of chiral magnets to deviations from hydrostaticity in quasihydrostatic high-pressure studies.

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Measuring the formation energy barrier of skyrmions in zinc-substituted Cu2OSeO3

Cited by 28 publications

References 52 publications

The optical tweezer of skyrmions

The optical tweezer of skyrmions

Stability and metastability of skyrmions in thin lamellae ofCu2OSeO3

In situ control of the helical and skyrmion phases in Cu2OSeO3 using high-pressure helium gas up to 5 kbar

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