Antiferromagnetic Ordering of MII(TCNE)[C4(CN)8]1/2 (M = Mn, Fe; TCNE = Tetracyanoethylene)

Abstract

The magnetic behaviors of MII(TCNE)[C4(CN)8]1/2 (M = Mn, Fe) prepared from a new synthetic route yielding purer magnetic materials are reported. Detailed DC magnetization and AC magnetic susceptibility measurements reveal that both compounds exhibit magnetic ordering with antiferromagnetic ground states arising from antiferromagnetically coupled ferrimagnetic layers with ordering temperatures of 69 and 84 K for polycrystalline M = Mn (Mn) and Fe (Fe), respectively. Because of the presence of two spin sites, these antiferromagnets are best described as compensated ferrimagnets. A spin flop transition between the antiferromagnetically coupled ferrimagnetic layers occurs at 19 500 Oe at 5 K for Mn, whereas Fe is a metamagnet. Fe also exhibits a constricted hysteretic behavior with a 5 K critical field of 12 600 Oe, and a coercive field and remanent magnetization of 4800 Oe and 1850 emu Oe/mol, respectively.