Regensburg 2013 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 20: Transport: Spincaloric Transport (jointly with MA)
TT 20.3: Vortrag
Montag, 11. März 2013, 15:30–15:45, H22
Spin-filtering efficiency of ferrimagnetic spinels CoFe2O4 and NiFe2O4 — Nuala Caffrey1, Daniel Fritsch2, Tom Archer1, Stefano Sanvito1, and •Claude Ederer3 — 1School of Physics and CRANN, Trinity College Dublin, Ireland — 2H. H. Wells Physics Laboratory, University of Bristol, United Kingdom — 3Materials Theory, ETH Zurich, Switzerland
We assess the potential of the ferrimagnetic spinel ferrites CoFe2O4 and NiFe2O4 to act as spin-filtering barriers in magnetic tunnel junctions. Our study is based on the electronic structure calculated by means of first-principles approaches within different approximations for the exchange correlation energy. We show that, in agreement with previous calculations, the densities of states suggest a lower tunneling barrier for minority spin electrons, and thus a negative spin-filter effect. However, a more detailed analysis based on the complex band-structure reveals that both signs for the spin-filtering efficiency are possible, depending on the band alignment between the electrode and the barrier material.