Volume 80, Number 1, October 2007
Article Number 17007
Number of page(s) 6
Section Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties
Published online 20 September 2007
EPL, 80 (2007) 17007
DOI: 10.1209/0295-5075/80/17007

Spin polarization at ferromagnet-insulator interfaces: The important role of stoichiometry in MgO/Fe(001)

Martina Müller, Frank Matthes and Claus M. Schneider

Institut für Festkörperforschung IFF-9 "Elektronische Eigenschaften", Forschungszentrum Jülich GmbH D-52425 Jülich, Germany

received 14 May 2007; accepted in final form 20 August 2007; published October 2007
published online 20 September 2007

The electronic structure of ferromagnet-insulator interfaces plays a key role in spin-dependent transport processes by determining the spin polarization of the tunneling charge carriers. Employing spin-polarized, angle-resolved photoelectron spectroscopy we studied the spin-resolved electronic structure in the model system MgO/Fe(001) and observed a surprisingly multifaceted influence of the MgO stoichiometry. In particular, oxygen-deficient MgO barriers are found to strongly enhance the interfacial spin polarization. The results highlight the important role of the specific nature of the oxygen bonding and its relevance for the tunnel magnetoresistance effect.

73.20.-r - Electron states at surfaces and interfaces.
73.40.Rw - Metal-insulator-metal structures.
73.40.Gk - Tunneling.

© Europhysics Letters Association 2007