Abstract
We study the tunneling magnetoresistance (TMR) effect in asymmetric ferromagnet/ferromagnet/ s-wave superconductor junctions based on the extended Blonder–Tinkham–Klapwijk theory. When the left ferromagnet (FM) is in the half-metallic limit, the low-energy charge transport in this system is governed by the so-called same-spin-band Andreev reflection, where the incident electron and the Andreev reflected hole belong to the same spin subband. It is demonstrated that the same-spin-band Andreev reflection depends sensitively on the relative orientation of the magnetizations in the two FMs leading to giant TMR effect (TMR > 10 6% for T/ T c ≪ 1). Distinctive oscillatory variation of TMR with the thickness or the spin polarization of the intermediate FM is also found.
Published Version
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