Direct Observation of Twisted Surface skyrmions in Bulk Crystals

Zhang, S. L.; Laan, G. van der; Wang, Weiwei; Haghighirad, Amir A.; Hesjedal, T.

doi:10.1103/physrevlett.120.227202

Cited by 85 publications

(91 citation statements)

References 45 publications

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“…Similar phenomenon in three-dimensional multilayer magnetic system was reported theoretically [28] and experimentally [29][30][31]. In the structure called threedimensional skyrmion, Bloch-like skyrmions are in the middle of the film and Néel-like skyrmions are at the top and bottom surface of the film.…”

Section: Resultssupporting

confidence: 81%

“…In the structure called threedimensional skyrmion, Bloch-like skyrmions are in the middle of the film and Néel-like skyrmions are at the top and bottom surface of the film. This structure has been observed in Fe/Gd multiplayers [29], FeGe nanodisk [30], and bulk Cu2OSeO [31]. The composite only including top layer and bottom layer of the three-dimensional skyrmion is called Néel caps.…”

Section: Resultsmentioning

confidence: 79%

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Magnetic structures in the locally inverted interlayer coupling region of a bilayer magnetic system

Lee

Kwon

Kim

et al. 2020

Journal of Magnetism and Magnetic Materials

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We investigate the magnetic structures in a bilayer magnetic system with the locally inverted interlayer coupling region using Monte Carlo simulation. Stabilization of multiple magnetic structures including the magnetic skyrmion is possible in the locally inverted interlayer coupling region. Various factors such as the region area, anisotropy, interlayer coupling strength, and exchange coupling strength affects the properties of the structures including its size and chirality. We obtain conditions for their stabilization and for the magnetic structural transitions. Dzyaloshinskii-Moriya interaction (DMI) and the dipolar interaction play a prominent role as they enhance the formation and the stability of structures significantly. An asymmetric feature can arise from the broken inversion symmetry in the structure formation, and it gives an interfacial DMI, which stabilizes the skyrmion. It is realized that the dipole interaction also acts as an effective interfacial DMI in the system.

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Section: Resultssupporting

confidence: 81%

Section: Resultsmentioning

confidence: 79%

Magnetic structures in the locally inverted interlayer coupling region of a bilayer magnetic system

Lee

Kwon

Kim

et al. 2020

Journal of Magnetism and Magnetic Materials

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“…Our appeal to T&T scattering for an interpretation of the diffraction pattern produced by PTO/STO superlattices illuminated with circularly polarized photons mirrors previous work for crystalline materials. 31,32 B. Charge-quadrupole moment for Ti 4+…”

Section: A Preamble and Surveymentioning

confidence: 99%

Resonant x-ray diffraction from chiral electric-polarization structures

Lovesey

Laan

2018

Phys. Rev. B

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Heterostructures of PbTiO3/SrTiO3 superlattices have shown the formation of "polar vortices", in which a continuous rotation of ferroelectric polarization spontaneously forms. Recently, Shafer et al. [Proc. Natl. Acad. Sci. (PNAS) 115, 915 (2018)] reported strong non-magnetic circular dichroism (CD) in resonant soft x-ray diffraction at the Ti L3 edge from such superlattices. The authors ascribe the CD to the chiral rotation of a polar vector. However, a polar vector is invisible to the parityeven electric-dipole transition which governs absorption in the soft x-ray region. A realistic, nonmagnetic explanation of the observed effect is found in Templeton-Templeton scattering. Following this route, the origin of the CD in Bragg diffraction is shown by us to be the chiral array of charge quadrupole moments that forms in these heterostructures. While there is no charge quadrupole moment in the spherically symmetric 3d 0 valence state of Ti 4+ , the excited state 2p 3/2 3d(t2g) at the Ti L3 resonance is known to have a quadrupole moment. Our expressions for intensities of satellite Bragg spots in resonance-enhanced diffraction of circularly polarized x-rays, including their harmonic content, account for all observations reported by Shafer et al. We predict both intensities of Bragg spots for the second harmonic of a chiral superlattice and circular polarization created from unpolarized x-rays, in order that our successful explanation of existing diffraction data can be further scrutinized through renewed experimental investigations. The increased understanding of chiral dipole arrangements could open the door to switchable optical polarization.I.

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“…We usually define the helicity of skyrmion by the phase χ [20] appearing in φ(ϕ) = N sk ϕ + χ, where the N sk is defined as the skyrmion number. In the recent year's studies [28,31], it is found that the skyrmion helicity can be decided by the combination of bulk and interfacial DMI. So the skyrmions with different DMI combinations, called by a joint name-the twisted(or hybrid) skyrmion, can have different helicities.…”

Section: Resultsmentioning

confidence: 99%

Spin current pumped by confined breathing skyrmion

Zhang¹,

Jin²,

Xia³

et al. 2020

New J. Phys.

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Spin pumping is a widely recognized method to generate the spin current in the spintronics, which can be found in varieties of magnetic materials and is acknowledged as a fundamentally dynamic process equivalent to the spin-transfer torque. In this work, we theoretically verified the oscillating spin current mixed by AC and DC components can be pumped from the microwave-motivated breathing skyrmion. The spin current can be pumped within a relatively low-frequency microwave compared with the in-plane ferromagnetic resonance (FMR). Although the amplitude of spin current density for a single confined skyrmion is several times lower than the FMR spin pumping, the pumped current would be improved to be the same order as the FMR through a tight skyrmion lattice. Based on the spin pumping of breathing skyrmion, we designed a high reading-speed racetrack memory model whose reading speed is much higher than the SOT (spin-orbit torque)/STT (spin-transfer torque) skyrmion racetrack. Our work focuses on the spin pumping phenomenon inside the breathing skyrmion, and it may contribute to the applications of the skyrmion-based device.

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Direct Observation of Twisted Surface skyrmions in Bulk Crystals

Cited by 85 publications

References 45 publications

Magnetic structures in the locally inverted interlayer coupling region of a bilayer magnetic system

Magnetic structures in the locally inverted interlayer coupling region of a bilayer magnetic system

Resonant x-ray diffraction from chiral electric-polarization structures

Spin current pumped by confined breathing skyrmion

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