A method based on optical and atomic force microscopes for instant imaging of non-homogeneous electro-mechanical processes and direct estimation of dij coefficients in piezoelectric materials at the local level

Pronounced and reversible modulation of the piezoelectric coefficients by a low magnetic field in a magnetoelectric PZT-5%Fe3O4 system

“…The insets of the upper panels, (a.i) and (a.ii), show photos of the specific samples together with an arbitrarily chosen coordinate system that assists us to define the symmetry axes x (SA x ) and y (SA y ). As it should be, the investigated area was at the sample edge, in the specific case onto SA y , as shown with a white dot for both samples (for details see ‘Section III’ of Supplementary Information and 37,38 ). Concerning the experimental procedure, six consecutive E ex,z loops were recorded designated by a loop index; first, without the application of H ex,z (loop index: 1 and 2), next, under the presence of H ex,z = 1 kOe (loop index: 3 and 4) and finally, when removing H ex,z (loop index: 5 and 6).…”

“…The constitutive Strain-Electric field curve, S(E ex,z ), of samples PZT-5%Fe 3 O 4 was estimated experimentally by using an OM-based technique already discussed in 37,38 for out-of-plane E ex,z up to 10 kV/cm. Here, we made another modification in the home-made aluminum platform hosting the sample, so that a constant, also out-of-plane magnetic field, H ex,z , is applied at will, by a NdFeB permanent magnet, (disc-shaped with diameter 20 mm and thickness 3 mm).…”

“…Concerning the experimental procedure, six consecutive E ex,z loops were recorded designated by a loop index; first, without the application of H ex,z (loop index: 1 and 2), next, under the presence of H ex,z = 1 kOe (loop index: 3 and 4) and finally, when removing H ex,z (loop index: 5 and 6). Figure 6(a.i,a.ii) present the mean absolute value of the in-plane PE coefficient in the y-direction, <|d zy |>, for the complete sequence of measurements (the other in-plane PE coefficient in the x-direction, d zx , is not shown since it is obviously zero 37,38 ). Specifically, these panels present explicit data on < |d zy | > before applying (loop index: 1 and 2), upon application (loop index: 3 and 4) and after removal (loop index: 5 and 6) of a constant H ex,z = 1 kOe.…”

“…We focus on the variation of the in-plane PE coefficients upon application of an E ex,z (ranging within ± 10 kV/cm) and a relatively low H ex,z (1 kOe), that are both applied out-of-plane at room temperature. By means of a method based on optical microscopy 37,38 , we showed in a direct way that the application of such a low H ex = 1 kOe, causes a pronounced decrease of the in-plane PE coefficients on the order of 50–60%, that intriguingly is restored upon successive removal of H ex . Polarization data showed that with the addition of the Fe 3 O 4 NPs, PZT becomes harder when compared to its plain form.…”

Degradation of the remanent ferromagnetic state under the action of ferroelectric relaxation processes in Co/(1−x)PMN-xPT/Co hybrids: Possible implications on cryogenic and room-temperature applications

“…For the same PMN-xPT crystals, at room temperature, the respective in-plane (that is along the surface) strain reads S % 0.03% for E ex ¼ þ2.5 kV/cm and S % 0.06% for E ex ¼ þ5.0 kV/cm (data not shown) as measured directly from the Strain-Electric field curve (for instance, see Figure 6 of Ref. 39 for PMN-xPT with x ¼ 0.27 and 0.31). Thus, we see that the increased strain correlates with increased m rem degradation.…”