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Tunable gigahertz dynamics of low-temperature skyrmion lattice in a chiral magnet

Lee, O; Sahliger, J; Aqeel, A; Khan, S; Seki, S; Kurebayashi, H; Back, CH; (2021) Tunable gigahertz dynamics of low-temperature skyrmion lattice in a chiral magnet. Journal of Physics: Condensed Matter , 34 (9) , Article 095801. 10.1088/1361-648X/ac3e1c. Green open access

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Abstract

Recently, it has been shown that the chiral magnetic insulator Cu2OSeO3hosts skyrmions in two separated pockets in temperature and magnetic field phase space. It has also been shown that the predominant stabilization mechanism for the low-temperature skyrmion (LTS) phase is via the crystalline anisotropy, opposed to temperature fluctuations that stabilize the well-established high-temperature skyrmion (HTS) phase. Here, we report on a detailed study of LTS generation by field cycling, probed by GHz spin dynamics in Cu2OSeO3. LTSs are populated via a field cycling protocol with the static magnetic field applied parallel to the ⟨100⟩ crystalline direction of plate and cuboid-shaped bulk crystals. By analyzing temperature-dependent broadband spectroscopy data, clear evidence of LTS excitations with clockwise (CW), counterclockwise (CCW), and breathing mode (BR) character at temperatures belowT= 40 K are shown. We find that the mode intensities can be tuned with the number of field-cycles below the saturation field. By tracking the resonance frequencies, we are able to map out the field-cycle-generated LTS phase diagram, from which we conclude that the LTS phase is distinctly separated from the high-temperature counterpart. We also study the mode hybridization between the dark CW and the BR modes as a function of temperature. By using two Cu2OSeO3crystals with different shapes and therefore different demagnetization factors, together with numerical calculations, we unambiguously show that the magnetocrystalline anisotropy plays a central role for the mode hybridization.

Type: Article
Title: Tunable gigahertz dynamics of low-temperature skyrmion lattice in a chiral magnet
Location: England
Open access status: An open access version is available from UCL Discovery
DOI: 10.1088/1361-648X/ac3e1c
Publisher version: http://doi.org/10.1088/1361-648X/ac3e1c
Language: English
Additional information: Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
Keywords: Lattice dynamics, magnetic order, magnetism, magnetization dynamics, skyrmions
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > London Centre for Nanotechnology
URI: https://discovery.ucl.ac.uk/id/eprint/10140723
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