Abstract
We investigate the interaction of tunnel barriers with Co and electrodes in light of their potential as room temperature spin filters. The question of the exchange coupling that often prohibits the independent switching between a magnetic tunnel barrier and its magnetic electrode is addressed, as is the difference between an oxide/metal and oxide/oxide system. Our study of the magnetic reversal in the and bilayers, supported by a detailed structural and chemical analysis of the samples and their interfaces, clearly evidences the effect of a metallic or an oxide interface. An unusual exchange spring magnet behavior arises in the case of the samples due to the superexchange interactions found in these ferrimagnetic oxides. This unique exchange phenomenon at the oxide-oxide interface ultimately leads to a bilayer system displaying a two-phase magnetization loop without the insertion of a nonmagnetic spacer.
- Received 9 November 2006
DOI:https://doi.org/10.1103/PhysRevB.75.224421
©2007 American Physical Society