In addition to the intrinsic modification of the electronic and magnetic properties of low dimensional systems due to their reduced dimensions, the extrinsic modification of the physical properties plays a crucial role. In this talk we present two examples of low dimensional systems (nanoparticles and nanometric thin films) consisting of transition metals (Fe and Co) whose magnetic properties are drastically modified depending on their surrounding environments. In both cases we will show that real systems are much more complex than expected due to new interfaces properties that become dominant in low dimensional objects.
We will first focus on the modification of the magnetic properties of an assembly of Fe nanoparticles deposited on Sapphire and capped either with polarisable (Pt and Pd) or with non-polarisable (Al) elements. We will show that alloying processes in such systems with reduced dimensions are likely to be mandatory for their magnetic properties.
The second part of the talk will be devoted to the modification of the magnetic and magneto-optical properties of nanometric Co films in multilayered Al/Co/V/MgO(100) structures. Evidence of the strong modification of the magnetic properties of the nanometric Co films in contact with the V thin films will be presented. In particular we show that the reduction of the Co magnetic moments in such systems propagates into the Co layers and that more than one layer of V is magnetically polarized, in contrast to recent results from theoretical calculations. Furthermore, we will show that magneto-optical simulations also suggest a long-range magnetization of the V atoms and a reduction of the Co atomic magnetic moments in agreement with the XMCD results.
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