Abstract
Tunnel electroresistance in ferroelectric tunnel junctions (FTJs) has attracted considerable interest, because of a promising application to nonvolatile memories. Development of ferroelectric thin-film devices requires atomic-scale band-structure engineering based on depolarization-field effects at interfaces. By using FTJs consisting of ultrathin layers of the prototypical ferroelectric BaTiO3, it is demonstrated that the surface termination of the ferroelectric in contact with a simple-metal electrode critically affects properties of electroresistance. BaTiO3 barrier-layers with TiO2 or BaO terminations show opposing relationships between the polarization direction and the resistance state. The resistance-switching ratio in the junctions can be remarkably enhanced up to 105% at room temperature, by artificially controlling the fraction of BaO termination. These results are explained in terms of the termination dependence of the depolarization field that is generated by a dead layer and imperfect charge screening. The findings on the mechanism of tunnel electroresistance should lead to performance improvements in the devices based on nanoscale ferroelectrics.
Original language | English |
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Pages (from-to) | 2708-2714 |
Number of pages | 7 |
Journal | Advanced Functional Materials |
Volume | 25 |
Issue number | 18 |
DOIs | |
Publication status | Published - 2015 May 13 |
Externally published | Yes |
Keywords
- electroresistance
- ferroelectric tunnel junctions
- metal-oxide interfaces
- surface termination
ASJC Scopus subject areas
- Chemistry(all)
- Materials Science(all)
- Condensed Matter Physics