Domain Engineering in BiFeO3 Thin films by Modifying the Substrate Termination and Symmetry

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Day / Time
Date(s) - 18/12/2015
10 h 00 min

Category


Séminaire DQMP – informel

Vendredi 18 décembre à 10h.00
Salle de réunion de la Datcha

A. Solmaz1, M. Huijben1, B. Noheda2, R. Egoavil3, N. Gauquelin3, J. Verbeeck3, G. Rijnders1
1Mesa+ Institute for Nanotechnology, University of Twente, Enschede, The Netherlands
2Zernike Institute for Advanced Materials, University of Groningen, The Netherlands
3EMAT, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp, Belgium

Multiferroics, such as BiFeO3, which simultaneously exhibit multiple order parameters such as antiferromagnetism and ferroelectricity, enable the development of novel magnetoelectric devices by utilizing the intrinsic magnetoelectric coupling. This could lead to new applications in magnetic data storage, spintronics, and high-frequency magnetic devices.

In this work, we focus on the heteroepitaxial growth of single crystal BiFeO3 thin films by pulsed laser deposition on termination modified SrTiO3 and orthorhombic TbScO3 substrates. Singly TiO2 terminated substrates can be switched to SrO termination by interval deposition with the assistance of Reflective High Energy Electron Diffraction (RHEED) technique. Our results demonstrate that BiFeO3 thin films grown on either SrO or TiO2 singly terminated substrates show different topographies as well as different ferroelectric domain patterns. Both the mobility of BiFeO3 species as well as the nucleation density are dependent on the substrate termination, and this influences the initial growth. In this talk, we will show that this plays a determining role for the rest of the growth; it leads to either a step flow or island like growth, consequently resulting in an atomically flat film surface or a rougher surface with island like features respectively. Additionally, change in the substrate surface symmetry between (110)o and (001)o cut TbScO3 substrates promotes the stabilization of different pairs of structural variants in the BiFeO3 thin films. This leads to formation of head-to-head and tail-to-tail domain wall configurations.

For device applications, as the film gets thinner the interfaces become more influential. Therefore interface engineering gains more importance for highly controlled multiferroic devices. We believe that our study shows the importance of having a control over the termination site of the substrates and surface symmetry.

Réalisation : Sur Mesure concept