Full text loading...
(a) Schematic illustration of experimental setup including gated Pt/Co/GdOx structure, focused laser beam to measure polar MOKE hysteresis loops, BeCu microprobe (1) to apply gate voltage V g, and W microprobe (2) to create local DW nucleation site to switch between DW nucleation and DW propagation limited magnetization reversal. White arrows illustrate local orientation of magnetization vector and DW nucleation beneath W probe tip. (b) Superposition of 6 individual MOKE hysteresis loops without landing W microprobe and (c) with W microprobe landed. (d) Switching field H c as a function of distance between MOKE probing spot and tip of landed W microprobe. Inset of (d) shows same data but with ln(d) plotted as function of H c − 1/ 4 .
Switching field H c in (a) DW nucleation and (b) DW propagation limited regime (i.e., W microprobe landed at d ∼ 80 µm) and (c) gate voltage V g plotted as a function of time. V g is ramped between −7.5 V and +7.5 V for 5 cycles and 50 MOKE hysteresis loops are averaged after every 0.5 V step in V g.
(a) Modification of switching field H c (i.e., ΔH c), (b) remnant to saturation magnetization ratio M r/M s, and (c) leakage current I L (clamped at 0.5 µA) as a function of time while gate voltage V g is ramped in steps of 0.5 V every ∼40 s (d). Left and right half of figure correspond to two different devices, measured under increasing negative and positive Vg, respectively. W microprobe is landed at d ∼ 80 μm and 250 MOKE hysteresis loops are averaged and I L is measured after every voltage step. Effects in regime I are linear and reversible. Regime II (enlarged in inset of (a)) is marked by the onset of irreversibility and, at higher V g, a steep drop in H c and M r/M s. Regime III corresponds to hard dielectric breakdown. Dashed area highlights lack of regime II for negative V g. Insets in (b) show representative hysteresis loops at indicated points.
Evolution of MOKE hysteresis loops measured for Pt/Co/GdOx/Ta/Au structure with reduced GdOx thickness of 3 nm. (a) Before application of gate voltage V g, (b) after application of V g = +1.8 V for 60 s, and (c) after subsequent application of V g = −1 V for 15 s.
Article metrics loading...