Toulouse, ConstanceFischer, J.Farokhipoor, S.Yedra Cardona, LluísCarlá, FrancescoJarnac, A.Elkaim, E.Fertey, P.Audinot, J.-N.Wirtz, TomNoheda, B.Garcia, V.Fusil, S.Peral Alonso, I.Guennou, M.Kreisel, J.2021-03-052021-03-052021-02-092475-9953https://hdl.handle.net/2445/174711Helium implantation in epitaxial thin films is a way to control the out-of-plane deformation independentlyfrom the in-plane strain controlled by epitaxy. In particular, implantation by means of a helium microscopeallows for local implantation and patterning down to the nanometer resolution, which is of interest for deviceapplications. We present here a study of bismuth ferrite (BiFeO3) films where strain was patterned locally byhelium implantation. Our combined Raman, x-ray diffraction, and transmission electron microscopy (TEM)study shows that the implantation causes an elongation of the BiFeO3unit cell and ultimately a transition towardsthe so-called supertetragonal polymorph via states with mixed phases. In addition, TEM reveals the onset ofamorphization at a threshold dose that does not seem to impede the overall increase in tetragonality. The phasetransition from the R-like to T-like BiFeO3appears as first-order in character, with regions of phase coexistenceand abrupt changes in lattice parameters.9 p.application/pdfeng(c) American Physical Society, 2021Pel·lícules finesHeliThin filmsHeliuminfo:eu-repo/semantics/article7076672021-03-05info:eu-repo/semantics/openAccess