Tatsuo HASEGAWA*, Seiichi KAGOSHIMA*, Tomoyuki MOCHIDA, S. SUGIURA** and Yoshihiro IWASA** (*Univ.Tokyo and **JAIST)
[Solid State Commun. 103, 489 (1997)]
Crystal structure, optical, and magnetic properties are investigated for a unique class of donor-acceptor charge-transfer complex, (BEDT-TTF)(F2-TCNQ). Charge-transfer from the donor to the acceptor is complete, forming an ionic mixed-stack CT crystal. "Side-by-side" interaction between BEDT-TTF molecules results in a one-dimensional correlated electronic system, which is perpendicular to the donor-acceptor mixed-stack column. Consequently, F2-TCNQ radical spins are strongly isolated from neighboring molecules, showing Curie-like behavior in magnetic susceptibility followed by an anti-ferromagnetic order at around TN = 30 K.