Dielectric and magnetic characterizations of capacitor structures with an ionic liquid/MgO barrier and a ferromagnetic Pt electrode

Abstract

The dielectric and magnetic properties of electric double layer (EDL) capacitor structures with a perpendicularly magnetized Pt/Co/Pt electrode and an insulating cap layer (MgO) are investigated. An electric field is applied through a mixed ionic liquid/MgO barrier to the surface of the top Pt layer, at which the magnetic moment is induced by the ferromagnetic proximity effect. The basic dielectric properties of the EDL capacitor are studied by varying the thickness of the MgO cap layer. The results indicate that the capacitance, i.e., the accumulated charge density at the Pt surface, is reduced with increasing the MgO thickness. From the MgO thickness dependence of the capacitance value, the effective dielectric constant of the ionic liquid is evaluated. Almost no electric field effect on the magnetic moment, the coercivity, or the Curie temperature is confirmed in the top Pt layer with the thickness of 1.3 nm, regardless of the presence or absence of the MgO cap layer, whereas the a clear change in the magnetic moment is observed when the top Pt layer is replaced by a Pd layer of 1.7 nm.

Dynamic electric-field-induced magnetic effects in cobalt oxide thin films: towards magneto-ionic synapses

“…This allows the synapse to be programmed with either excitatory signals (via a positive weight) or inhibitory signals (via a negative weight), mimicking the brains capability to increase/decrease the membrane potential of postsynaptic neurons under certain conditions. So far, electricfield control of magnetism has primarily relied on the following strategies: 19 (i) the use of single-phase multiferroic materials with intrinsic magnetoelectric coupling, 25,26 (ii) electric charge accumulation in ferromagnetic metals or semiconductors 27,28 and (iii) piezostrain-mediated effects through inverse magnetostriction in ferromagnetic/ferroelectric heterostructures. [29][30][31] The implementation of these approaches in marketable devices is hampered by several factors.…”