Shaping the magnetic anisotropy of nickel films by coupling with piezoelectricity
Converting magnetic excitation into electrical energy is of great interest for medical applications, such as remote implant charging. In a previous article, members of INSP showed that a Ni/LiNbO3/Ni composite produces a strong magnetoelectric (ME) effect under weak excitation (1 Oe, 100–300 kHz), without a static magnetic field, thanks to the magnetic and structural anisotropy of Ni films. The team continued the study by exploring the origin of this anisotropy, which is surprising for very thick Ni films (2 µm). The researchers studied the coupling between a polycrystalline film and a single-crystal LiNbO3 substrate. The initial quasi-isotropic strain is released by annealing (up to 250 °C), and the anisotropy intensifies along the crystalline axes of the substrate, in connection with its anisotropic thermal expansion. By peeling off the film, the interfacial origin of the phenomenon is demonstrated. This result sheds new light on magnetostrictive-piezoelectric interactions in hybrid composites.
Reference
Seyed Alireza Mirfakhraie, Louis Christienne, Tianwen Huang, Loïc Becerra, David Hrabovsky, Hakeim Talleb, Aurélie Gensbittel, Pauline Rovillain, Yunlin Zheng, and Massimiliano Marangolo, « Inducing in-plane structural and magnetic anisotropy in a thick polycrystalline nickel film coupled to LiNbO3 substrate » J. Phys. D: Appl. Phys. 58, 165301 (2025)
Caption: Coupling between a magnetostrictive film (Ni) and a piezoelectric (LiNbO3). (a) Grazing incidence X-ray diffraction of the Ni 311 reflection along the Z or c-axis (in red) and the X or a-axis (in blue) of LiNbO3 where the vertical dashed line indicates the expected diffraction angle for the Ni bulk. (b) Ni 311 reflection of the film after annealing at 250°C. (c) In-plane magnetic anisotropy of the Ni film after annealing at 250°C: hysteresis cycles along the Z and X axes of LiNbO3, respectively. (d) In-plane magnetic isotropy of the Ni film peeled off the substrate where the inset shows a portion of the Ni film peeled off from LiNbO3 and placed on a Si wafer for handling.
