Determining exchange splitting in a magnetic semiconductor by spin-filter tunneling.
PHYSICAL REVIEW LETTERS 2008;
101:147201. [PMID:
18851564 DOI:
10.1103/physrevlett.101.147201]
[Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2008] [Indexed: 05/26/2023]
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, Phys. Rev. Lett. 86, 3847 (2001)10.1103/Phys. Rev. Lett.86.3847].
Collapse