Premium
Interface and Surface Cation Stoichiometry Modified by Oxygen Vacancies in Epitaxial Manganite Films
Author(s) -
Li Zhipeng,
Bosman Michel,
Yang Zhen,
Ren Peng,
Wang Lan,
Cao Liang,
Yu Xiaojiang,
Ke Chang,
Breese Mark B. H.,
Rusydi Andrivo,
Zhu Weiguang,
Dong Zhili,
Foo Yong Lim
Publication year - 2012
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201200143
Subject(s) - materials science , manganite , stoichiometry , epitaxy , oxygen , pulsed laser deposition , monolayer , chemical physics , thin film , analytical chemistry (journal) , nanotechnology , condensed matter physics , ferromagnetism , layer (electronics) , chemistry , physics , organic chemistry , chromatography
Perovskite manganites are viewed as one of the key building blocks of oxide spintronics devices due to their attractive physical properties. However, cation off‐stoichiometry at epitaxial interfaces between manganites and other materials can lead to interfacial dead layers, severely reducing the device performance. Here, transmission electron microscopy and synchrotron‐based spectroscopy are used to demonstrate that oxygen vacancies during growth serve as a critical factor for modifying the cation stoichiometry in pulsed laser deposited La 0.8 Sr 0.2 MnO 3 films. Near the film/substrate (SrTiO 3 ) interface, A‐site cations (La/Sr) are in excess when oxygen vacancies are induced during film growth, partially substituting Mn. Simultaneously, Sr cations migrate towards the film surface and form a SrO rock‐salt monolayer. Consequentially, a gradient of the Mn nominal valence is observed along the film growth direction, leading to anomalous magnetic properties. The results narrow the selection range of useful oxygen pressures during deposition and demonstrate that accurate cation stoichiometry can only be achieved after oxygen vacancies are eliminated during growth. This finding suggests that the oxygen pressure serves as a tuning parameter for the interfacial dead layers and, hence, for control over device properties.