posted on 2020-03-13, 14:09authored byCristina Navarro-Senent, Alberto Quintana, Eloy Isarain-Chávez, Eugen Weschke, Pengmei Yu, Mariona Coll, Eva Pellicer, Enric Menéndez, Jordi Sort
Effective
manipulation of the magnetic properties of nanostructured metallic
alloys, exhibiting intergrain porosity (i.e., channels) and conformally
coated with insulating oxide nanolayers, with an electric field is
demonstrated. Nanostructured Co–Pt films are grown by electrodeposition
(ED) and subsequently coated with either AlOx or HfOx by atomic layer deposition
(ALD) to promote magneto-ionic effects (i.e., voltage-driven ion migration)
during electrolyte gating. Pronounced variations in coercivity (HC) and magnetic moment at saturation (mS) are found at room temperature after biasing
the heterostructures. The application of a negative voltage results
in a decrease of HC and an increase of mS, whereas the opposite trend is achieved for
positive voltages. Although magneto-ionic phenomena are already observed
in uncoated Co–Pt films (because of the inherent presence of
oxygen), the ALD oxide nanocoatings serve to drastically enhance the
magneto-ionic effects because of partially reversible oxygen migration,
driven by voltage, across the interface between AlOx or HfOx and the nanostructured
Co–Pt film. Co–Pt/HfOx heterostructures
exhibit the most significant magneto-electric response at negative
voltages, with an increase of mS up to
76% and a decrease of HC by 58%. The combination
of a nanostructured magnetic alloy and a skinlike insulating oxide
nanocoating is shown to be appealing to enhance magneto-ionic effects,
potentially enabling electrolyte-gated magneto-ionic technology.