Determining Exchange Splitting in a Magnetic Semiconductor by Spin-Filter Tunneling

T. S. Santos, J. S. Moodera, K. V. Raman, E. Negusse, J. Holroyd, J. Dvorak, M. Liberati, Y. U. Idzerda, and E. Arenholz

Phys. Rev. Lett. 101, 147201 – Published 30 September 2008

Abstract

A large exchange splitting of the conduction band in ultrathin films of the ferromagnetic semiconductor EuO was determined quantitatively, by using EuO as a tunnel barrier and fitting the current-voltage characteristics and temperature dependence to tunneling theory. This exchange splitting leads to different tunnel barrier heights for spin-up and spin-down electrons and is large enough to produce a near-fully spin-polarized current. Moreover, the magnetic properties of these ultrathin films ( $< 6 nm$ ) show a reduction in Curie temperature with decreasing thickness, in agreement with theoretical calculation [R. Schiller et al., Phys. Rev. Lett. 86, 3847 (2001)].

Received 24 June 2008

DOI:https://doi.org/10.1103/PhysRevLett.101.147201

Authors & Affiliations

T. S. Santos^1,*, J. S. Moodera¹, K. V. Raman¹, E. Negusse², J. Holroyd², J. Dvorak², M. Liberati², Y. U. Idzerda², and E. Arenholz³

¹Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
²Department of Physics, Montana State University, Bozeman, Montana 59717, USA
³Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA

^*Present address: Argonne National Laboratory, Argonne, IL, USA.

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Vol. 101, Iss. 14 — 3 October 2008

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