Piezostrain tuning non-volatile 90° magnetic easy axis rotation in Co₂FeAl Heusler alloy film grown on Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃heterostructures

Shear-strain-mediated magnetoelectric effects revealed by imaging

“…3d) and E 3 = +1 MV m -1 (Fig. 3g) are also consistent with the hitherto expected 90 rotation of a global easy axis 25,26,29,35,47,49,51 created by poling. This is because both the first (E 1  E 2 ) and second (E 2  E 3 ) field steps appear to interconvert the hard and easy directions, as seen more clearly by comparing polar plots of magnetic-hysteresis-loop squareness at each electric field (blue data, Fig.…”

“…These extrema in magnetization are consistent with the expected 25 extrema in macroscopic strain (Fig. S4b, Supplementary Note 3), which have been hitherto understood to drive 90 rotations of a global magnetic easy axis 25,26,29,35,47,49,51 . The minima in M y correspond to a ~50% change of magnetization, and a peak ME coupling coefficient of (Fig.…”

“…However, the angular resolution of the colour wheel is insufficient for visual inspection to confirm that the local magnetization typically rotated by the 90 that one would expect from our macroscopic measurements (blue data, Fig. 3c,f,i), previous macroscopic measurements 25,26,29,35,47,49,51 , and previous microscopic measurements 29,35 . Plotting the pixel magnetization directions in our vector maps on polar plots (red data, Fig.…”

“…However, if the out-of-plane component of polarization is electrically switched on and off then the in-plane component is necessarily modified (71 and 109 switching), such that the resulting change of in-plane strain permits non-volatile ME effects 25,26 . In practice, the global magnetic easy axis has been reported to undergo electrically driven 90 rotations 25,26,29,35,47,49,51 , consistent with a dominant component of normal strain along y  [01 ̅ 1] c (ref. 48).…”

Long‐Range Nonvolatile Electric Field Effect in Epitaxial Fe/Pb(Mg1/3Nb2/3)0.7Ti0.3O3 Heterostructures

“…In general, in the Fe (4, 15, and 30 nm)/PMN‐PT heterostructure, coexistence of a piezostrain and a charge effect is expected. Based on our previous reports, the piezostrain effect originates in the ferroelectric substrate and can be transferred to the ferromagnetic thin film to mediate the magnetic parameters so that the dependence of these parameters on the applied electric field always shows butterfly‐like characteristics. From this aspect, if the piezostrain effect has a dominant role in the system, the strain‐electric field ( S – E ) curve having a butterfly‐like characteristics, as shown in Figure S3a of the Supporting Information, can lead to a similar butterfly‐like H r – E curve.…”