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Magneto-ionics is an approach that enables the energy-efficient tuning of magnetic properties by electrochemical charging. Materials with a high surface-to-volume ratio are particularly suitable for this purpose. In the present work [1], we prepared a nanoporous Pd75Co25 alloy by dealloying the precursor Al80(Pd75Co25)20, achieving pore sizes in the range of 10 nm.
In-situ SQUID magnetometry, in combination with a detailed electrochemical analysis, reveals that the reversible reduction/formation of surface-based Co oxides and hydroxides leads to substantial variations in the magnetization. In fact, a switching between a weakly magnetic OFF state, and a ferromagnetic ON state, characterized by a significantly enhanced saturation magnetization, can be achieved using this voltage-triggered electrochemical reaction. Furthermore, with specific electrochemical measurement techniques, a second, smaller magneto-ionic effect based on the absorption/desorption of hydrogen was observed in the same alloy.
Ongoing experiments focus on investigating the behavior of both magneto-ionic effects in Pd-Co alloys of varying compositions.
[1] S. Eber et al., ACS Mater. Au., 2026, in press. (DOI: 10.1021/acsmaterialsau.5c00245)