When a Lamb wave propagates on a plate engraved by a periodic grating, it may exhibit attenuation. This attenuation is related to a coupling of this incident mode with other propagating modes. As the propagation takes place in a periodic medium, the dispersion curves of the modes are of interest because they exhibit passbands and stopbands related to the geometry of the waveguide. The goal of this work is to quantitatively establish the relation between the value of the attenuation of the propagating waves and the width of the forbidden bands appearing inside the Brillouin zone. This study is performed by using a finite element method (ATILA code).

We have demonstrated pressure-induced transition in a c-axis oriented vanadium sesquioxide (V₂O₃) thin film from a strongly correlated metal to a Mott insulator in a submicrometric region by inducing a local stress using contact atomic force microscopy. To have an access to a pressure range of sub-gigapascal, a tip with a large radius of 335 nm was prepared by chemical vapour deposition of platinum onto a commercial tip with a focused ion beam (FIB). The FIB-modified tip gives a good electrical contact at low working pressures (0.25–0.4 GPa) allowing unambiguously to evidence reversible metal-insulator transition in a pulsed laser-deposited V₂O₃ thin film by means of local investigations of current-voltage characteristics. A finite element method has confirmed that the diminution of the c/a ratio under this tip pressure explains the observed phase transition of the electron density of states in the film.

The piezoelectric properties of compositional spread (1 − x)BiFeO₃-xGaFeO₃ epitaxial thin films are investigated where Ga³⁺ substitution for Bi³⁺ is attempted in Bi_1−xGa_xFeO₃ compounds. Ga content x was varied from 0 to 12% (atomic). Ferroelectric characterizations are reported at various length scales. Around 6.5% of Ga content, an enhancement of the effective piezoelectric coefficient ${\mathrm{d}}_{33}^{\text{eff}}$ is observed together with a change of symmetry of the film. Measured ${\mathrm{d}}_{33}^{\text{eff}}$ values in 135 nm thick films increased from 25 pm/V for undoped BiFeO₃ to 55 pm/V for 6.5% Ga with no extrinsic contribution from ferroelastic domain rearrangement.

We prepared a stacked structure consisting of a quasi-free-standing functional oxide thin film and a ceramic piezoelectric disk and observed the effect of the piezoelectric disk deformation on the resistance of the thin film. Epitaxial V₂O₃ films were grown by a pulsed laser deposition method on muscovite mica substrates, peeled off using Scotch tapes, and transferred onto piezoelectric elements. In this V₂O₃/insulator/top electrode/piezoelectronic disk/bottom electrode structure, the resistance of the V₂O₃ film displayed a variation of 60% by sweeping the piezoelectronic disk bias. With support from x-ray diffraction measurements under an electric field, a huge gauge factor of 3 × 10³ in the V₂O₃ film was inferred. The sizeable resistance change in the V₂O₃ layer is ascribed to the piezo-actuated evolution of c/a ratios, which drives the material towards an insulating phase. A memory effect on the resistance, related to the hysteretic displacement of the piezoelectric material, is also presented.