Self-assemblies of colloidally prepared magnetic nanoparticles provide a convenient and tunable material architecture to produce tunneling magnetoresistance, which has become a dominant sensing technology in the past few decades. These assemblies contain innumerous interparticle junctions which can modulate spin currents based on their magnetic state. This magnetoresistance behavior is highly dependent on the magnetic properties of the constituent nanoparticles, which are modulated by the nanoparticles' size, shape, and surface chemistry. Despite the wide parameter space available to explore, previous studies on nanoparticle magnetoresistance have focused largely on homogenous materials consisting of single phases, sizes, and shapes. We prepared several nanoparticle inks with distinct, synthetically-selected magnetic properties to investigate emergent properties in more complex nanoparticle assemblies. Using a combination of magnetically hard CoFe2O4 and magnetically soft Fe3O4, we have generated pseudo spin valve magnetoresistance in a composite film, which surpasses the sensitivity of the constituents alone.

Engineering pseudo spin valve magnetoresistance in colloidally prepared nanoparticle films

2019 Fall National Meeting

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