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Ducarme et al. - 2026 - Data-driven Thiele equation approach for state-dependent coefficients in the nonlinear dynamics of v.pdf
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Abstract
(en) Spin-torque vortex oscillators provide a model system for the nonlinear dynamics of a confined magnetic texture. Their motion is commonly described by the Thiele equation, but its standard form keeps the gyrovector and damping tensor fixed at their rigid-vortex values and becomes inaccurate at large gyration amplitudes. We introduce a data-driven Thiele equation approach that extracts effective, position-dependent Thiele coefficients from a single current-ramp micromagnetic simulation by interpolating the magnetization in vortex-core-position space. The extracted maps reveal a weak increase of the gyrovector magnitude and a pronounced separation of the radial and azimuthal dissipation as the orbit expands, providing quantitative signatures of confinement-and motion-induced vortex deformation. Because the gyrotropic, dissipative, conservative, and spin-transfer contributions retain their usual Thiele structure, the resulting description remains physically interpretable rather than acting as a black-box surrogate. Incorporating these state-dependent coefficients into the equation reproduces the nonlinear stable-orbit dynamics and accurately predicts the response to time-varying currents, whereas a conventional constant-coefficient description predicts vortex expulsion. The framework therefore provides a systematic route for deriving effective collective-coordinate dynamics from full micromagnetic states with high computational efficiency.
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Ducarme, C., de Wergifosse, S., Coppee, T., da Câmara Santa Clara Gomes, T., & Abreu Araujo, F. (2026). Data-driven Thiele equation approach for state-dependent coefficients in the nonlinear dynamics of vortex-based nano-oscillators. Physical Review B, 114(19), 194404. https://doi.org/10.1103/4dbr-s8mw (Original work published 2026)