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We have shown that the magnetic properties of nanoparticles may be tuned from superparamagnetic to ferromagnetic by changing the substrate or thin film matrix in which they are embedded. Nickel nanoparticles were embedded into alumina, titanium nitride, and cerium oxide matrices on both silicon and sapphire substrates via pulsed laser deposition. The laser ablation time on the nickel target was kept constant. Only nickel nanoparticles in cerium oxide showed characteristics of ferromagnetism (room temperature coercivity and remanence). Ni nanoparticles, in either alumina or titanium nitride, possessed blocking temperatures below 200 K. Detailed scanning transmission electron microscopy analysis has been conducted on the samples embedded into cerium oxide on both substrates and related to the magnetic data. [ABSTRACT FROM AUTHOR]

We investigate the effect of nickel nanoparticle size on thermal transport in multilayer nanocomposites consisting of alternating layers of nickel nanoparticles and yttria stabilized zirconia (YSZ) spacer layers that are grown with pulsed laser deposition. Using time-domain thermoreflectance, we measure thermal conductivities of k=1.8, 2.4, 2.3, and 3.0 W m-1 K-1 for nanocomposites with nickel nanoparticle diameters of 7, 21, 24, and 38 nm, respectively, and k=2.5 W m-1 K-1 for a single 80 nm thick layer of YSZ. We use an effective medium theory to estimate the lower limits for interface thermal conductance G between the nickel nanoparticles and the YSZ matrix (G>170 MW m-2 K-1), and nickel nanoparticle thermal conductivity. [ABSTRACT FROM AUTHOR]