VP13-10 Magneto-Ionic Vortices: Voltage-Controlled Curling-Spin Analog-Memory Nanomagnets
Creators: Irena Spasojevic
Zheng Ma
Aleix Barrera
Federica Celegato
Alessandro Magni
Sandra Ruiz-Gomez
Michael Foerster
Anna Palau
Paola Tiberto
Kristen S. Buchanan
Jordi Sort
Publisher: name: IEEE
Year: 2025

Control of magnetism through electric-field-induced ion motion (magneto-ionics) is poised to reshape existing voltage actuation approaches, aimed at bolstering energy efficiency across a diverse spectrum of spintronics and magnetically driven devices. However, despite the pressing need for strategies to control magnetic states at the nanoscale, most magneto-ionic studies to date have focused on continuous films [1-4]. Here we will demonstrate in-situ probing of ion motion in nanometer-sized structures, revealing the presence of dynamically evolving spin configurations, strongly dependent on the gating duration. More precisely, we will introduce a so far unexplored nanoscale magnetic object: an analog magnetic vortex controlled by electric-field-driven ion motion (i.e., magneto-ionic vortex or, for simplicity, “vortion”) [5]. This state is generated from a paramagnetic material (in our case FeCoN) via in-situ voltage application and subsequent gradual extraction of N3– ions within patterned nanodots. What distinguishes vortions from conventional magnetic vortex states is that their key properties, such as amplitude of magnetization, nucleation and annihilation fields, coercivity, remanence and anisotropy, can be controlled and fine-tuned in an analog and reversible manner using an energy-conscious voltage gating process. This manipulation occurs post-synthesis, obviating the need for energy-demanding methods like laser pulses or spin-torque currents. By taking an advantage of a so far overlooked aspect of N3– magneto-ionics—occurrence of a planar ion migration front —control of the magnetic layer's thickness is achieved in the nanodots, enabling reversible transitions among paramagnetic, single-domain, and vortion states, offering future prospects for analog computing, in e.g. brain-inspired devices.References: [1] U. Bauer et al., Nat. Mater., vol 14, p. 174-181 (2015). [2] J. De Rojas et al., Nat. Commun., vol. 11, p. 5871 (2020). [3] A. Quintana et al., ACS Nano, vol 12, p. 10291-10300 (2018). [4] K. Duschek et al., J. Mater. Chem. C., vol 6, p. 8411-8417 (2018). [5] I. Spasojevic et al., arXiv:2403.13722 [cond-mat.mtrl-sci] (2024). (at review stage) Acknowledgements This work has been supported by the European Research Council (2021-ERC-Advanced REMINDS Grant N 101054687).
Control of magnetism through electric-field-induced ion motion (magneto-ionics) is poised to reshape existing voltage actuation approaches, aimed at bolstering energy efficiency across a diverse spectrum of spintronics and magnetically driven devices. However, despite the pressing need for strategies to control magnetic states at the nanoscale, most magneto-ionic studies to date have focused on continuous films [1-4]. Here we will demonstrate in-situ probing of ion motion in nanometer-sized structures, revealing the presence of dynamically evolving spin configurations, strongly dependent on the gating duration. More precisely, we will introduce a so far unexplored nanoscale magnetic object: an analog magnetic vortex controlled by electric-field-driven ion motion (i.e., magneto-ionic vortex or, for simplicity, “vortion”) [5]. This state is generated from a paramagnetic material (in our case FeCoN) via in-situ voltage application and subsequent gradual extraction of N3– ions within patterned nanodots. What distinguishes vortions from conventional magnetic vortex states is that their key properties, such as amplitude of magnetization, nucleation and annihilation fields, coercivity, remanence and anisotropy, can be controlled and fine-tuned in an analog and reversible manner using an energy-conscious voltage gating process. This manipulation occurs post-synthesis, obviating the need for energy-demanding methods like laser pulses or spin-torque currents. By taking an advantage of a so far overlooked aspect of N3– magneto-ionics—occurrence of a planar ion migration front —control of the magnetic layer's thickness is achieved in the nanodots, enabling reversible transitions among paramagnetic, single-domain, and vortion states, offering future prospects for analog computing, in e.g. brain-inspired devices.References: [1] U. Bauer et al., Nat. Mater., vol 14, p. 174-181 (2015). [2] J. De Rojas et al., Nat. Commun., vol. 11, p. 5871 (2020). [3] A. Quintana et al., ACS Nano, vol 12, p. 10291-10300 (2018). [4] K. Duschek et al., J. Mater. Chem. C., vol 6, p. 8411-8417 (2018). [5] I. Spasojevic et al., arXiv:2403.13722 [cond-mat.mtrl-sci] (2024). (at review stage) Acknowledgements This work has been supported by the European Research Council (2021-ERC-Advanced REMINDS Grant N 101054687).