Magnetization of (ET)2- and κ-(BETS)2-FeCl4

Both (ET)2FeCl4 and κ-(BETS)2FeCl4 have Fe3+ ions in the anion layer. The former is a semiconductor with an energy gap of 0.12 eV and the latter remains normal metallic down to below 0.5 K. Their magnetizations, which are very similar to each other, are scaled by the Brillouin function (S=5/2) modified by the effective temperature T* = T − Θ. The Weiss temperature Θ is estimated^to be −3 K and −1K for ET and BETS salts, respectively. Both systems are concluded to have the high spin states (S = 5/2) of Fe3+ ions which are antiferromagnetically interacting each other very weakly.