Berlin 2012 – wissenschaftliches Programm
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DF: Fachverband Dielektrische Festkörper
DF 1: Focus Session: Conductive Domain Walls
DF 1.4: Hauptvortrag
Montag, 26. März 2012, 10:55–11:25, EB 107
Mechanisms and control of conduction through domain walls in BiFeO3 thin films — •Saeedeh Farokhipoor and Beatriz Noheda — Zernike Institute, Univ. of Groningen, The Netherlands
BiFeO3 (BFO) has become widely popular not only because it is the only room temperature, antiferromagnetic ferroelectric, but also because of the interesting sequence of phase transitions that it can display. In BFO thin films under epitaxial strain different types of domain walls can be obtained with very high control, which has allowed systematic investigation of the distinct properties of domains walls. It was revealed that artificially-written 109o and 180o domain walls in BFO thin films show enhanced conductivity with respect to the domains[1]. This promises to enable novel nano-devices and has initiated further work on the mechanisms that control ferroelastic domain wall conductivity in BFO[2,3] and other ferroelectrics[4,5]. Here we show that highly-stable, as-grown, 71o domain walls of BFO conduct as good as or better than written 109o walls and that the main mechanism for conduction is thermionic emission of electrons from the top electrode (the conductive tip of an atomic force microscope). The tunability and control of the current by engineering the tip-BFO Schottky barrier using various routes will also be discussed.
[1] J. Seidel et al. Nat. Mat. 8, 229 (2009); [2] J. Seidel et al. Phys. Rev. Lett. 105, 197603 (2010); [3] S. Farokhipoor and B. Noheda Phys. Rev. Lett. 107, 127601 (2011); [4] P. Maksymovych et al. Nanotechn. 22, 254031 (2011); [5] J. Guyonnet et al. Adv. Mater., DOI: 10.1002/adma.201102254