Current-driven Magnetic Skyrmions for Encoding/Storing Information: Manipulation and Dynamics in Nanoscale Structures

Jiang, Yunxi ORCID: 0000-0002-2284-8470 (2025) Current-driven Magnetic Skyrmions for Encoding/Storing Information: Manipulation and Dynamics in Nanoscale Structures PhD thesis, University of Liverpool.

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Abstract

This dissertation investigates the dynamics of current-driven magnetic skyrmions, topological solitons in magnetic materials with broken spatial inversion symmetry, for low-power spintronic applications like racetrack memory and multilevel data storage. Skyrmions’ small size and low driving current requirements make them promising information carriers. The research examines skyrmion motion under driving currents, pinning effects, and thermal fluctuations, using numerical simulations (Landau-Lifshitz-Gilbert equation), analytical studies (Thiele equation), and theoretical modeling to design novel data storage devices. The study analyzes skyrmion motion amidst pinning potentials from material imperfections. Simulations reveal that thermal fluctuations vary with damping: acting as a frictional force at low damping or a driving force aiding depinning at high damping. The Thiele equation quantifies this, though its accuracy wanes at low temperatures with pinning. The skyrmion Hall angle, influenced by current and pinning, provides insights for ambient-condition devices. These findings underpin a proposed multilevel data storage device, where controlled current positions skyrmions at pinning sites for high-density, low-power encoding. The research also explores altermagnetic (ATM) skyrmions, which exhibit d-wave symmetry via exchange-driven spin splitting. Simulations and modeling reveal a 90$^\circ$ interlayer orientation in elliptical skyrmion pairs, validated by $C_4$ symmetry and anisotropic Berry curvature, with exchange difference ($J_1$ - $J_2$) modulating anisotropy. This positions ATM skyrmions as topological probes for spintronics. Additionally, the study investigates current-induced spin waves in magnetic tracks, deriving their dispersion and amplitude. Simulations show spin wave deviation and domain wall generation, controllable by current density, enabling applications in memory, logic, and neuromorphic computing. These insights advance spintronic technologies. The multilevel storage device addresses high-density, low-power needs, while discoveries about thermal fluctuations, ATM skyrmions, and spin waves enhance the understanding of topological magnetic structures. This work lays a foundation for energy-efficient, high-performance spintronic devices.

Item Type:	Thesis (PhD)
Uncontrolled Keywords:	Skyrmions, Nanoscale Structures
Divisions:	Faculty of Science & Engineering Faculty of Science & Engineering > School of Physical Sciences Faculty of Science & Engineering > School of Physical Sciences > Physics
Depositing User:	Symplectic Admin
Date Deposited:	11 Feb 2026 09:41
Last Modified:	11 Feb 2026 10:24
DOI:	10.17638/03194985
Supervisors:	Yu, Hao Xuan, Chen Sharma, Hem Raj
URI:	https://livrepository.liverpool.ac.uk/id/eprint/3194985
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