Neutron diffraction studies of the first purely organic ferromagnetic crystal

Abstract

The first purely organic ferromagnetic material, the β form of the para-nitrophenyl nitronyl nitroxide p-NPNN, was studied by single crystal neutron diffraction. A zero field unpolarized neutron experiment performed in the temperature range 50–800 mK provides the first direct evidence of spontaneous ferromagnetic bulk ordering below TC = 0.67 K. The data obtained in the polarized neutron experiment was used to reconstruct the spin density distribution and explain the mechanisms of magnetic interaction.