Bistable Spin-Crossover Nanoparticles Showing Magnetic Thermal Hysteresis near Room Temperature


  • This work was supported by the Spanish Ministry of Education and Science (MEC) (Projects CTQ2005-09385-C03-01 and MAT2004-3849). M.M.C. also thanks the MEC for a predoctoral fellowship. Supporting Information is available online from Wiley InterScience or from the author.


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Nanoparticles exhibiting a cooperative spin transition, prepared using the reverse micelle technique, are reported. A 40 K magnetic hysteresis is observed near room temperature for [Fe(Htrz)2(trz)](BF4) nanoparticles (where trz is a triazole derivative) of 11 ± 5 nm in diameter. The figure shows the nanoparticles in octane in the low-spin state (left) and the high-spin state (right).