SPONTANEOUS MAGNETIZATION AT 36K IN A SULFUR-NITROGEN RADICAL

The radical p-NCC6F4CNSSN, 1, can be obtained in two different phases depending upon sublimation conditions. The alpha-phase, 1 alpha, cryst allises in space group P (1) over bar, and the molecules are related t hrough an inversion centre. The beta-phase, 1 beta, crystallises in th e orthorhombic space group Fdd2 and the molecules are not related by a n inversion centre. The latter shows a sharp rise in the magnetic susc eptibility at 36K which is accompanied by an out-of-phase component in the a.c. susceptibility. Heat capacity measurements show a distinct p eak at 35.5K indicative of the long range ordering of the magnetic mom ents. The magnetic ordering of the compound is also confirmed by neutr on diffraction experiments. Magnetisation isotherms indicate the prese nce of a small residual moment that saturates below 100 Oe. Extrapolat ion of the residual moment at T = 0K gives a value for the spontaneous magnetisation of 1.5 x 10(-3) mu(B)/molecule. The behaviour is interp reted in terms of weak ferromagnetism.