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

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). Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2089/2007/c0559_s.pdf or from the author. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.