The FeCo material was synthesized in nanoparticle form in a TiN/FeCo/TiN sandwich structure using a pulsed laser deposition (PLD) method. FeCo is significantly cheaper than noble metal based bimetallic materials such as Fe-Pt, Ni-Pd, etc. A Fe-0.5 Co-0.5 composition was chosen in this study which is based on the local spin-density electronic-structure calculations. The advantage of this structure is in-situ passivation of FeCo nanoparticles by TiN thin films which is highly stable against atmospheric ambient conditions. TiN/FeCo/TiN samples with variable FeCo nanoparticle size were made by changing the number of laser pulses impinging on a chemically synthesized composite FeCo target. By controlling the particle size in the confined layers, it was possible to tune the magnetic properties from superparamagnetic to ferromagnetic in a controlled way. Magnetic hysteresis characteristics below the blocking temperature are consistent with single-domain behavior. (C) 2013 Elsevier B.V. All rights reserved.