We have measured the susceptibility and low-temperature magnetization curve
of the novel organic tetraradical crystal BIP-TENO. The susceptibility dat
a indicate that double-spin chains of ferromagnetic dimers are formed in th
e; crystal and the spin system is regarded as an S = 1 antiferromagnetic tw
o-leg ladder. The magnetization is nearly zero up to 100kOe and the spin ga
p is closed at 116kOe. Above 120kOe, the magnetization increases and a plat
eau corresponding to a quarter of the saturation magnetization appears at 4
48 kOe. (C) 2001 Elsevier Science B.V. All rights reserved.