Influence of δ-layers on indirect exchange coupling in giant magnetoresistance multilayers

Author： Perez M. Marrows C. H. Hickey B. J.

E-ISSN： 1286-4854|54|2|262-268

ISSN： 0295-5075

Source： EPL (EUROPHYSICS LETTERS), Vol.54, Iss.2, 2010-03, pp. : 262-268

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Abstract

The effects of four different kinds of impurity δ-layerinserted into the Co layer of Co/Cu multilayers were investigated.Two completely different behaviours were found. Very smallfractions of a monolayer of Ta or Cr increased the remanence ofour multilayers up to almost 100%, destroying completely thegiant magnetoresistance (GMR). This does not happen when an evenlarger amount of Cu or Pd is embedded in the Co layer, goodantiferromagnetic coupling is maintained. In this case theremanence of the structure only increases by 20% for roughly anorder of magnitude higher quantity of material, and naturally thisstill gives good values of the GMR. The decrease of the GMR isentirely explained in terms of a loss of antiferromagneticalignment due to weaker indirect exchange coupling over the Cuspacer —even though this spacer layer remains pure Cu. Theseeffects have been explained in terms of the magnetic properties ofthe different elements used as impurity affecting the spin-dependent reflectivity for electrons of the Co/Cu interfaces.