Spin filtering with EuO: Insight from the complex band structure

Authors

Pavel Lukashev, University of Nebraska-LincolnFollow
Aleksander L. Wysocki, University of Nebraska-LincolnFollow
Julian P. Velev, University of Puerto RicoFollow
Mark van Schilfgaarde, King's College LondonFollow
Sitaram Jaswal, University of Nebraska-LincolnFollow
Kirill D. Belashchenko, University of Nebraska-LincolnFollow
Evgeny Y. Tsymbal, University of Nebraska at LincolnFollow

Date of this Version

2012

Document Type

Article

Citation

PHYSICAL REVIEW B 85, 224414 (2012); DOI: 10.1103/PhysRevB.85.224414

Comments

Copyright 2012 American Physical Society. Used by permission.

Abstract

Spin-filter tunneling is a promising way to create highly-spin-polarized currents. So far the understanding of the spin-filtering effect has been limited to a free-electron description based on the spin-dependent tunneling barrier height. In this work we explore the complex of EuO as a representative ferromagnetic insulator used in spin-filter tunneling experiments and show that the mechanism of spin filtering is more intricate than it has been previously thought. We demonstrate the importance of the multiorbital band structure with an indirect band gap for spin-filter tunneling. By analyzing the symmetry of the complex bands and the decay rates for different wave vectors and energies we draw conclusions about spin-filter efficiency of EuO. Our results provide guidelines for the design of spin-filter tunnel junctions with enhanced spin polarization.