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Geometrical and compositional structure at metal-oxide interfaces: MgO on Fe(001)
H L Meyerheim1, R Popescu, J Kirschner
1Max-Planck Institut für Mikrostrukturphysik, Weinberg 2, D-06120 Halle, Germany.
Physical Review Letters
|August 11, 2001
Summary
Surface X-ray diffraction revealed an unexpected iron oxide (FeO) interface layer during magnesium oxide (MgO) deposition on iron (Fe). This finding impacts understanding of Fe/MgO interfaces and tunneling magnetoresistance.
Area of Science:
- Materials Science
- Surface Science
- Condensed Matter Physics
Background:
- Understanding thin film growth on magnetic substrates is crucial for spintronic devices.
- The interface structure of MgO on Fe(001) is key to phenomena like tunneling magnetoresistance.
- Previous models assumed direct contact between MgO and Fe(001).
Purpose of the Study:
- To precisely determine the geometric structure of MgO deposited on Fe(001).
- To investigate the interfacial layer, if any, between MgO and the Fe(001) substrate.
- To re-evaluate the commonly accepted growth model for MgO on Fe(001).
Main Methods:
- Ultrahigh vacuum deposition of MgO on Fe(001) via electron evaporation.
- Detailed structural analysis using surface X-ray diffraction (SXRD).
Main Results:
- The study identified an unconsidered iron oxide (FeO) interface layer.
- This FeO layer exists between the Fe(001) substrate and the growing MgO film.
- The MgO film grows on top of this FeO interfacial layer, not in direct contact with Fe(001).
Conclusions:
- The growth of MgO on Fe(001) involves an intermediate FeO layer.
- This discovery necessitates a revision of the Fe/MgO/Fe(001) interface model.
- The findings offer new insights into the tunneling magnetoresistance effect.