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Article Dans Une Revue New Journal of Physics Année : 2014

Long-ranged magnetic proximity effects in noble metal-doped cobalt probed with spin- dependent tunnelling

Résumé

We inserted non-magnetic layers of Au and Cu into sputtered AlOx-based magnetic tunnel junctions and Meservey-Tedrow junctions in order to study their effect on tunnelling magnetoresistance (TMR) and spin polarization (TSP). When either Au or Cu are inserted into a Co/AlOx interface, we find that TMR and TSP remain finite and measurable for thicknesses up to several nanometres. High-resolution transmission electron microscopy shows that the Cu and Au interface layers are fully continuous when their thickness exceeds ∼3 nm, implying that spin-polarized carriers penetrate the interface noble metal to dis- tances exceeding this value. A power law model based on exchange scattering is found to fit the data better than a phenomenological exponential decay. The discrepancy between these length scales and the much shorter ones reported from x-ray magnetic circular dichroism studies of magnetic proximitization is ascribed to the fact that our tunnelling transport measurements selectively probe s-like electrons close to the Fermi level. When a 0.1 nm thick Cu or Au layer is inserted within the Co, we find that the suppression of TMR and TSP is restored on a length scale of ≲1 nm, indicating that this is a sufficient quantity of Co to form a fully spin-polarized band structure at the interface with the tunnel barrier.
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Dates et versions

hal-00983903 , version 1 (25-04-2014)

Identifiants

Citer

Mihai S. Gabureac, Donald A. Mac Laren, Hervé Courtois, Christopher M. Marrows. Long-ranged magnetic proximity effects in noble metal-doped cobalt probed with spin- dependent tunnelling. New Journal of Physics, 2014, 16, pp.043008. ⟨10.1088/1367-2630/16/4/043008⟩. ⟨hal-00983903⟩

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