Abstracts Book - IMRC 2018

• SD4-O021
FERROELECTRIC MODULATED ELECTRON RECONSTRUCTION
AT RAlO3/SrTiO3 INTERFACES PROBED BY ELECTRON
MICROSCOPY AND SPECTROSCOPY
Di Wu 1
1 Nanjing University, Nantional Lab. of Solid State Microstructures and Department of Materials
Science and Engineering, China.
Perovskite RAlO 3 (R=La, Nd, Sm and Gd) films have been deposited epitaxially on
(001) TiO 2 -terminated SrTiO 3 substrates. The structure and electron
reconstruction at the interface are characterized by aberration-corrected
transmission electron microscopy and electron energy loss spectroscopy.
Electron transfer across the RAlO 3 /SrTiO 3 interface and the 2-dimensional
transport are observed very sensitive to the species of rare-earth element, that
is to chemical strain. First-principles calculations reveal the competition
between ionic polarization and electronic polarization in the polar layers in
compensating the build-in polarization due to the polar discontinuity at the
interface. The large ionic polarization in SmAlO 3 /SrTiO 3 and GdAlO 3 /SrTiO 3
hence reduces the amount of electrons transferred. Then, Pb(Zr x Ti 1-x )O 3 capping
layers with different polarization directions are deposited on LaAlO 3 /SrTiO 3
heterostructures. Ferroelectric polarization is used to modulate the electron
reconstruction at the LaAlO 3 /SrTiO 3 interface. In Pb(Zr x Ti 1-x )O 3 /LaAlO 3 /SrTiO 3
heterostructures, electron energy loss spectroscopy reveals that PZT
polarization pointing opposite (toward) the interface suppresses (enhances) the
electron transfer at the LaAlO 3 /SrTiO 3 interface.
Keywords: STEM, EELS, interface reconstruction
Presenting authors email: diwu@nju.edu.cn