Control of magnetic anisotropy in Pt/Co system using ionic liquid gating

Abstract

The magnetic anisotropy of the Pt/Co system under ionic liquid gating was studied. A comparison of results obtained using samples under the gating and those subjected to mild oxidization by oxygen plasma ashing suggested that the anodic oxidization of the Co layer could be one of the causes of the large modulation observed in the magnetic anisotropy. However, the charge accumulation effect was probably dominant when the Co layer was on the cathode side. The experiments presented here are expected to aid in elucidating the mechanism by which electric fields affect magnetism.

Co thin films deposited directly on ZnO polar surfaces

“…R Hall n decreased with μ 0 H || , showing that the magnetization of the sample tilts from being perpendicular to the plane to the in-plane direction. Based on the R Hall n - μ 0 H || curve, the normalized magnetization along the hard axis ( M hard n ) is obtained using the following relationship: M hard n  = sin[arccos( R Hall n )](refs 28, 29, 30). The results at 10 K for the three samples are shown in Fig.…”

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

“…Electric double layer (EDL) capacitors using ionic liquids have been intensively studied, because much larger electric field application can be realized in this case compared with solid state capacitors. 4,[10][11][12][13][14][15] There have been a number of reports on the electric field effect on magnetism in metallic magnetic materials using EDL capacitors, such as a large change in the Curie temperature T C for ultra-thin layers of Co, 4 magnetic signal enhancement in non-magnetic Pt, 11 modulation of the proximity-induced magnetic moment in Pd, 12 and highly efficient electric field modulation of the magnetic anisotropy in ferromagnetic Pd. 13 An identification of the difference of the mechanism (the charge accumulation effect or the redox [16][17][18] ) has also been discussed using an EDL capacitor with a Co electrode.…”

“…The system has the perpendicular magnetic anisotropy owing to the Co/Pt interface. The Pt layer shows an fcc(111) structure from x-ray diffraction measurement 14 and transmission electron microscopy 19 (not shown). At this Pt thickness (= 1.3 nm), we expect a magnetic moment to be induced at the surface of the top Pt layer.…”

“…13 An identification of the difference of the mechanism (the charge accumulation effect or the redox [16][17][18] ) has also been discussed using an EDL capacitor with a Co electrode. 14 In this paper, we focus on the EDL capacitor with a Pt electrode, where a magnetic moment is induced owing to the proximity effect from an adjacent ferromagnetic Co underlayer. The Pt surface is capped with an insulating MgO layer and further covered by an ionic liquid to form the EDL by application of V G .…”

“…19 To form the EDL capacitor, an ionic liquid film (ILF), an elastic polymer films containing ionic liquid, is used. 4,[12][13][14][15] The ionic liquid used here is TMPA-TFSI (N,N,N-trimethyl-N-propylammonium bis(trifluoromethanesulfonyl)imide). The ILF is placed directly on the bottom electrode.…”