Magnetic anisotropy induced by structural texture in BiFeO3 PLD thin films deposited over Si substrates

GRECIA A. GOMEZ-INIARTE, D. M. SOUZA; L.A. S. DE OLIVEIRA; A. MELLO; L. STEREN, S. CARREIRA; A. PENTON-MADRIGAL; J.P. SINNECKER

Honolulu

Conferencia; 59th Annual Magnetism and Magnetics Materials Conference; 2014

AIP plus Magnetic Society

The BiFeO3 (BFO) compound is one of the most studied multiferroic material, either in bulk, nanoparticles or in the form of thin films [1-3]. In the present study we evaluate the microstructure and magnetic behaviour Pulsed Laser Deposition (PLD) BFO thin films grown over Si substrates, in terms of the thickness and the film deposition rate. In thin films, the residual stresses arising from effects related to the interface film/substrate may induce structural and physical properties changes. The residual microstrain is associated with several factors: the intrinsic deformation due to the film growth process, the thermal strains related to different thermal expansion coefficients of the substrate and film and presence of minority spurious phases as result of local phase transformations during film growth. All of these factors affect the properties of the material. Thin films of BFO deposited by PLD over Si substrates, were obtained from pure BFO targets. The PLD depositions were made using a pulsed laser Nd: YAG with a wavelength of 355 nm focused on the target. A set of samples produced with different conditions, i.e., varying the position of the substrate relative to the plume and the deposition rate that affects significantly the thin film microstructure.  The films were annealed at 600o C for 10 min. The X-ray diffraction experiments (XRD) were conducted at the LNLS/Campinas XRD2 beam line in grazing angle mode with a wavelength of 1.2398 Å and incident angle of 5o, with 2 varying from 10 to 50o, using a step of 0.02o with fixed counting time. The produced thin films exhibit texture, with preferred orientation of the (024) planes almost parallel to the samples surface. The magnetic characterization, performed in a Quantum Design PPMS, shows a ferromagnetic behavior at room temperature and an in-plane magnetic anisotropy due to the microstructural texture of the samples.[1] G. Catalan and F. Scott, Adv. Mater., 21, 2463 (2009).[2] D. Lebeugle et al. Phys. Rev. Lett. 100,[3] P. Tae-Jin et al. Nano Letters  7(3), 766 (2007)