(Color online) (a) Schematic illustration of the ferromagnetic thin film/actuator hybrid with the contact scheme in van der Pauw geometry. The external magnetic field H is oriented along x for all measurements. (b) M(H) loops recorded at fixed voltages V p showing a magnetically easy loop for V p = +30 V (red squares) and a hard loop for V p = −30 V (blue circles) along x. (c) Hysteretic strain-voltage curve of the actuator showing that the strain εy (V p) exhibits two distinct strain states at V p = 0 V (big open circles) depending on V p history.
(Color online) (a)-(d) M(H) loops at fixed V p for a V p upsweep from V p = −30 V to V p = +30 V (full black squares) and a subsequent V p downsweep (open green circles). The lines are guides to the eye. (e)-(h) Simultaneously recorded R (H) loops (symbols). The solid lines display simulations of the AMR in a single-domain model showing very good overall agreement with the experiment. The mechanical hysteresis of the actuator results in significant differences between V p up- and downsweep in the MOKE loops [(b), (c)], which is also reflected in the AMR curves [(f), (g)].
(Color online) Coercive field μ 0 H c (a) and normalized remanent magnetization M r/M s (b) extracted from the M (H) loops shown in Figs. 2(a)–2(d). Both quantities exhibit the hysteretic behavior characteristic of the mechano-elastic hysteresis of the actuator. (c) Two consecutive R (V p) loops recorded at μ 0 H = 0 mT, after preparing a single-domain magnetic state. A single voltage cycle starts at V p = +30 V, followed by a V p downsweep (open green circles) and a subsequent upsweep (full black squares). The curves also consistently show a hysteretic behavior. The solid lines depict the AMR calculated based on the corresponding M (V p) loops, showing very good agreement with the experimental AMR data. (d) Macrospin magnetization orientation α, calculated from the measured AMR data displayed in (c) with the AMR parameters given in the text (solid black and green lines), and from the measured MOKE data (dashed gray lines). At V p = 0 V, M can be reversibly switched between two magnetization orientation states, which corresponds to a M reorientation of Δα = 15°. In the full voltage range −30 V ≤ V p ≤ +30 V, M can be reversibly adjusted within 55°.
(Color online) (a) Magnetic preparation sweep at V p = +30 V to establish a well-defined magnetization state. After sweeping from μ 0 H = +120 mT to 0 mT (point A) the magnetic field is kept fixed at μ 0 H = 0 mT. (b) Illustration of the data acquisition process. The data is recorded at V p = 0 V (gray bar) after applying a voltage sequence either V p = 0 V → +30 V → 0 V (red line) or V p = 0 V → −30 V → 0 V (blue line). (c) Demonstration of repeated electro-elasto-magnetic switching processes, with M (full black symbols) and R (open purple symbols) being recorded five times in each acquisition window (gray). (d) Electro-elasto-magnetic memory-bit response for other acquisition windows.
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