Switching a magnetic bit—the fundamental operation in magnetic memories—relies on electric currents. This leads to significant energy losses and heat dissipation. In a world increasingly driven by data, reducing this energy cost has become a major technological challenge. A promising alternative is magneto-ionics: instead of using electric current to manipulate magnetism, voltage is used to drive the motion of ions and induce redox processes. Because the current involved in voltage-driven processes is minimized, energy dissipation can be potentially reduced, opening the door to low-power memory and computing devices.

In antiferromagnetic materials, neighboring spins align in opposite (antiparallel) directions, resulting in no net magnetisation. For this reason, antiferromagnets are considered magnetically “invisible”. This property makes them particularly attractive for technologies where magnetic information could remain hidden and also allows bits to be packed more closely together since there are no stray magnetic fields causing interference between neighboring elements.

While magneto-ionics has been widely explored in ferromagnetic systems—modulating properties such as saturation magnetisation, coercivity, or magnetic anisotropy—its potential in antiferromagnetic materials has remained rather unexplored. When a ferromagnet is adjacent to an antiferromagnet, the interaction between the two magnetic phases can produce upon field-cooling setting an interfacial spin-coupling effect known as exchange bias, a key operating principle in many magnetic memory technologies. A clear signature of this phenomenon is a shift of the magnetization versus magnetic field (M-H) hysteresis loop along the applied magnetic field axis.

A new international study involving researchers from ICN2 and the UAB, published in ACS Nano, demonstrates that exchange bias can be generated, suppressed, and tuned at room temperature through a magneto-ionic process in a single antiferromagnetic NiCoO layer. The work included Simone Privitera, under the supervision of ICREA Prof. Jordi Sort (UAB, Leader of the ICN2 Nanomaterials for Advancing Memory and Computing Group), Prof. Enric Menéndez (UAB), and Prof. Aitor Lopeandia (UAB). It also featured contributions from researchers at the Institute of Radiation Physics (Helmholtz-Zentrum Dresden–Rossendorf), the Universidade Tecnológica Federal do Paraná, Université Paris-Saclay, and Spin-Ion Technologies.

An innovative way to control magnetism

In contrast to conventional approaches, their new method avoids the thermal treatments typically required for thin-film fabrication as well as for setting the exchange bias direction, thereby enhancing energy efficiency, since NiCoO is grown under an applied magnetic field. Moreover, the entire functionality is achieved within a single layer.

These results pave the way for programmable exchange bias controlled by magneto-ionics and open a path toward using voltage to hide magnetic data, potentially enabling new anti-hacking strategies in future magnetic memory technologies. The work is also appealing for antiferromagnetic spintronics applications.

Reference article:

Privitera, S.; Ma Z., Gómez-Torres, H.; Arredondo-López, A.; Liedke, M.O.; Hirschmann, E.; Wagner, A., Tan, H.; Solsona, P.; Quintana, A., A.; Dias, T.; Gouéré, D.; Monteblanco, E., Ravelosona, D.; Del-Valle, N.; Navau, C.; Lopeandia, A.; Sort, J., Menéndez, E. Voltage-Driven Generation of Ferromagnetism in a Magneto-Ionically Active Antiferromagnet Enabling Room-Temperature Exchange Bias. ACS Nano. (2026) https://pubs.acs.org/doi/10.1021/acsnano.5c19864