WEAK FERROMAGNETISM AND ANTIFERROMAGNETIC ORDERING OF 2P ELECTRONS INTHE ORGANIC RADICAL COMPOUND 2,4,6-TRIPHENYLVERDAZYL

High-quality sizable single crystals of the radical compound 2,4,6-tri phenylverdazyl (TPV) have been prepared and their magnetic properties investigated by neutron-diffraction and magnetization measurements. Ne utron-diffraction peaks corresponding to long-range antiferromagnetic ordering have been observed below the Neel temperature of 1.78 K. The determined spin structure has intrachain antiferromagnetic coupling ex tending toward the c axis with the spins aligned to the b axis. Magnet ization measurements also reveal that weak ferromagnetism appears belo w T(N) with the ferromagnetic components in directions parallel and pe rpendicular to the spin direction. The magnetization curve shows no hy steresis, which is consistent with small anisotropy of 2p electrons in organic magnets.