The exponential rise of Big Data is driving a dramatic increase in energy consumption by information technologies [1]. One reason is that most memory systems utilize electric currents to write data, which inherently dissipates energy through Joule heating [2]. Electric-field control of magnetic properties has emerged as a sustainable leading strategy to address this issue. Among the diverse voltage-driven mechanisms for the tuning of magnetism (e.g. electrostatic charging, strain-mediated multiferroic coupling or electrochemical reactions [3]), control of magnetism through electric-field-induced ion motion in magneto-ionics is rapidly gaining momentum. Magneto-ionics provides unprecedented non-volatile control of coercivity, anisotropy, exchange bias or magnetization, ultimately enabling conversion between magnetic and non-magnetic states [4,5]. However, despite the pressing need for strategies to control magnetic states at the nanoscale, magneto-ionics has largely been confined to continuous thin films, leaving nanoscale magnetic architectures underexplored.

In this talk, we will demonstrate in-situ probing of magnetic properties and associated ion dynamics in nanometer-scale structures, revealing dynamically evolving spin configurations that strongly depend on the gating duration. More precisely, we will introduce a so far unexplored nanoscale magnetic object: magnetic vortex controlled by electric-field-driven ion motion, termed the magneto-ionic vortex or, for simplicity, “vortion” [6]. Vortions are generated within initially paramagnetic FeCoN nanodots via voltage-driven gradual extraction of N^3– ions. What distinguishes vortions from conventional magnetic vortex states is that their key properties such as magnetization amplitude, nucleation and annihilation fields, coercivity, remanence and anisotropy, can be controlled and fine-tuned post-synthesis in an analog, reversible and energy-efficient manner [6]. This obviates the need for energy-demanding methods like laser pulses or spin-torque currents. Such tunability is made possible by taking advantage of a so far overlooked aspect of N^3– magneto-ionics, namely the occurrence of a planar ion migration front, which allows precise, post-synthesis control of the magnetic layer's thickness. Consequently, we demonstrate voltage-mediated transitions between paramagnetic, single-domain, and vortion states, unlocking a new paradigm for energy-efficient control of magnetism at the nanoscale.

This unprecedented level of control over magnetic properties at the nanoscale and at room temperature opens new horizons for the development of advanced magnetic devices with functionalities that can be tailored at the post-synthesis stage, therefore providing enhanced flexibility, needed to meet specific technological demands. Magneto-ionic states induced within patterned units enable transformative potential for neuromorphic devices [7], analog computing, multi-state data storage, and adaptive inference protocols implemented directly within magneto-ionic architectures [8]. Moreover, we find that the inherent physical nature of patterned magneto-ionic systems enables robust, self-protected hardware security primitives–crucial as Big Data growth outpaces the reliability of software-based defenses [8]. These findings pave the way for a new class of hardware security solutions rooted in emergent magnetic phenomena.