Monday 4.10.2010, 14:15-15:15 Spielzimmer EP4


EuO, spin filtering with a ferromagnetic semiconductor

Massimo Barbagallo

Cavendish Laboratory, University of Cambridge, UK

EuO is a ferromagnetic semiconductor interesting for spintronics and quantum computation applications. I will discuss the importance of this material and the research in progress at the Cavendish Laboratory in Cambridge, UK. So far, we have carried out both experimental and theoretical studies of the magnetic properties of thin films of oxygen deficient EuO. Accurate control of the oxygen vacancy concentration in these films was achieved by sputter co-deposition of Eu and Eu_2 O_3 . The films were characterized by X-ray diffraction, SQUID, X-ray reflectometry and polarized neutron reflectometry and the magnetic moment was found to increase monotonically with excess electron concentration. The electronic structure of EuO_1-x was calculated using density functional theory (DFT+U). In agreement with previous studies, these calculations show that oxygen vacancies act as n-type dopants in EuO and that the excess electrons preferentially populate the majority spin branch of the spin polarized conduction band. The observed increase in the magnetic moment originating from these excess electrons was accurately determined experimentally and found to be in good agreement with our quantitative predictions.