Magnetocurrent of Charge-Polarizable C60-Diphenylaminofluorene Monoadduct-Derived Magnetic Nanocomposites

We demonstrated the strategy of a nanocomposite design by the incorporation of both a delocalized pi-electrons system in a closely bound acceptor-donor analogue chromophore, based on charge-polarizable C-60(>DPAF-C-9) nanostructure 1, and spin-polarized d-electrons in the form of gamma-FeOx nanoparticles. Facile intramolecular electron transfer from the DPAF-C-9 donor moiety to the C-60 acceptor cage of 1 upon activation to the excited state with a long lifetime of the charge-separated state forms a possible mechanism to integrate semiconducting and magnetic properties in a single system. We observed an appreciable magnetocurrent (MC) of C-60(>DPAF-C-9)-encapsulated magnetic gamma-FeOx nanoparticles in PMMA matrix upon applying a magnetic field from 0 to 300 mT at either 77K (12% MC) or 300 K (4.5% MC). Interestingly, the detailed analysis of magnetocurrent curve profiles taken at 77 K allowed us to conclude that the measured magnetocurrent may be attributed to the contributions from magnetic field-dependent excited-state populations in semiconducting structure (density-based MC), magnetism from magnetic structure (mobility-based MC), and product of density and mobility-based MC components (pi-d electronic coupling). At the higher temperature region up to 300 K, the semiconducting mechanism dominated the determining factor of measured magnetocurrent. This experimental observation indicated the feasibility of combining delocalized pi electrons and spin-polarized d electrons through charge transfer to induce internally coupled dual mobility- and density-based MC through the modulation of spin polarization and excited states in semiconducting/magnetic hybrid materials.