Controlled enhancement or suppression of exchange biasing using impurityδlayers

Abstract

The effects of inserting impurity δ-layers of various elements into a Co/IrMn exchange biased bilayer, at both the interface, and at given points within the IrMn layer a distance from the interface, has been investigated. Depending on the chemical species of dopant, and its position, we found that the exchange biasing can be either strongly enhanced or suppressed. We show that biasing is enhanced with a dusting of certain magnetic impurities, present at either at the interface or sufficiently far away from the Co/IrMn interface. This illustrates that the final spin structure at the Co/IrMn interface is not only governed by interface structure/roughness but is also mediated by local exchange or anisotropy variations within the bulk of the IrMn.

Exchange bias and training effect in Ni/Ag-doped NiO bilayers

“…2 and 3. These Ag nanoparticles are somewhat like a discontinuous interfacial nonmagnetic dusting layer inserted into the NiO/Ni exchange biased bilayers [20][21][22]. Recent studies have revealed that even the submonolayer dusting layers can strongly weaken the exchange coupling due to the screening effect of these dusting layers [20,22].…”

Spin polarization and exchange coupling of Cu and Mn atoms in paramagnetic CuMn diluted alloys induced by a Co layer

“…We have undertaken x-ray resonant magnetic scattering ͑XRMS͒ measurements combined with x-ray magnetic circular dichroism ͑XMCD͒ to study the proximity effect by determining the moment of delta-doped 12 high-susceptibility impurities in close proximity to a ferromagnetic layer. The interface sensitivity of the XRMS technique is ideal for characterizing the spatial extent of the spin polarization.…”

Large exchange bias enhancement in (Pt(or Pd)/Co)/IrMn/Co trilayers with ultrathin IrMn thanks to interfacial Cu dusting

“…In contrast, a 10% H ex increase was reported with Pt dusting. 21 The authors inferred that the addition of Pt, similarly to what is observed in perpendicular-to-plane exchange biased materials, 23 locally enhances the AF anisotropy because PtMn has a larger anisotropy than IrMn. Clearly, this explanation cannot be put forward to explain the enhancement of exchange bias with Cu dusting in the present experiments.…”

“…However, T B is always enhanced in the trilayer systems compared to the corresponding bilayers. 21 Another interesting observation concerns the exchange bias amplitude: At room temperature, the trilayers exhibit a larger H ex than the bilayers for t Cu < 0.6 nm; below 100 K, the opposite situation occurs. For instance, at 4 K, the maximum hysteresis loop shift is of about 580 Oe and 820 Oe for the trilayers and the bilayers, respectively.…”