Vortex configurations as a source of reconfigurable collective dynamics in dipolarly coupled spin-torque vortex oscillator arrays
(2026) MRS Fall 2026 — Location: Boston (US) (29.November.2026)
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- Spin-torque vortex oscillators are promising building blocks for unconventional computing owing to their nonlinear dynamics, frequency tunability, and ability to synchronize through magnetic interactions in arrays [1–4]. To increase their combined emission power, coupling these devices to achieve synchronization is beneficial [5]. While electrical interconnection provides a direct route to synchronization, implementing all-to-all coupling in dense nanoscale arrays remains challenging. An alternative approach for high-density integration is to exploit the stray fields generated when oscillators are driven by large current densities, enabling communication through dipolar interactions. Previous theoretical [6] and experimental studies [7] have mainly focused on dipolar-coupling-induced synchronization, highlighting the dominant role of vortex polarity. Here, we investigate the collective dynamics of dipolarly coupled STVO arrays through a combination of electrical measurements and micromagnetic simulations. Experimentally, spin-diode measurements on two- and three-oscillator arrays reveal multiple collective dynamical states. Following stochastic vortex nucleation, the devices can exhibit distinct resonance spectra characterized by either a single collective resonance or multiple separated modes. Since vortex states differ only by chirality and polarity, these hidden degrees of freedom likely underlie the observed spectral reconfigurability. Furthermore, transitions between collective states can be induced through current and magnetic field pulses, which have previously been demonstrated to selectively control vortex chirality and polarity [8], while additional switching between collective dynamical states is observed at high excitation power, consistent with vortex core expulsion and renucleation processes. Although chirality and polarity remain experimentally inaccessible, DC resistance measurements confirm the number of vortices in the array. To identify the physical origin of this reconfigurability, we perform micromagnetic simulations with independently controlled vortex chirality and polarity and realistic frequency dispersion introduced through oscillator radius variations. We find that vortex chirality strongly influences the collective dynamics through chirality-dependent frequency shifts induced by the Oersted field [9] and through modifications of the dipolar interactions governing frequency locking. Consequently, multiple synchronized and partially synchronized states can be achieved without modifying the network geometry or bias conditions. For a triangular three-oscillator system, five distinct collective dynamical responses are obtained, including desynchronized, partially synchronized, and fully synchronized regimes. In a four-oscillator square array, the same mechanism enables all synchronization regimes, from independent oscillation to complete locking, including intermediate two- and three-oscillator synchronized states. These results provide a plausible explanation for the experimentally observed spectral reconfiguration and identify vortex chirality as a powerful hidden degree of freedom for engineering multistate oscillator networks for oscillator-based and neuromorphic computing. [1] J. Torrejon et al., Nature, vol. 547, pp. 428–431 (2017). [2] H. Jung et al., ACS Nano, vol. 6(5), pp. 3712–3717 (2012). [3] J. Grollier et al., Nature Electronics, vol. 3, pp. 360–370 (2020). [4] D. Li et al., Physical Review B, vol. 86, p. 014418 (2012). [5] A. Ruotolo et al., Nature Nanotechnology, vol. 4(8), pp. 528–532 (2009). [6] A. D. Belanovsky et al., Applied Physics Letters, vol. 103(12), p. 122405 (2013). [7] N. Locatelli et al., Scientific Reports, vol. 5, p. 17039 (2015). [8] A. S. Jenkins et al., Applied Physics Letters, vol. 105(17), p. 172404 (2014). [9] Y. S. Choi et al., Applied Physics Letters, vol. 93(18), p. 182508 (2008).
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de Wergifosse, S., Jenkins, A., Araujo, P., Gonçalves, D., Cardoso de Freitas, S., Gartside, J., Abreu Araujo, F., & da Câmara Santa Clara Gomes, T. (2026). Vortex configurations as a source of reconfigurable collective dynamics in dipolarly coupled spin-torque vortex oscillator arrays. MRS Fall 2026, Boston (US). https://hdl.handle.net/2078.5/277097