Unconventional Properties of TTF-Based Organic Magnetic Conductors
Unconventional magnetic properties of various TTF-based π-d interaction systems are presented. (D)2FeBr4 (D=DMET, EDTDM) are quasi-2D metals consisting of alternating stacking of donor π-electron conducting sheets and square lattice d-spins of FeBr4 - anion sheets. The magnetoresistance is strongly affected by changes of Fe3+ spin arrangement in the ordered state. Especially, for (EDTDM)2FeBr4, a large negative magnetoresistance appears in the vicinity of an MI transition. In (EDO-TTFBr2)2FeX4 (X=C1, Br) having similar sandwich structure to (D)2FeBr4, the presence of the Br atom of the donor bonded semicovalently to X atom of FeX4 - gives strong π-d interaction, which produces a strong correlation between the electron transport and magnetism in addition to a high Néel temperature with a complicated spin structure. (EDO- TTFI2)M(mnt)2 (M=Ni, Pt) are featured by a combination of 1D metal of EDO-TTFI2 columns and 1D ferromagnetic chain of M(mnt)2. For M=Pt, weak AF inter-chain interaction brings about a metamagnetic feature. The application of pressure enhances ferromagnetic features with an anomalous hysteretic hump.
KeywordsEasy Axis Localize Magnetic Moment Spin Density Wave Central Metal Atom Magnetic Anion
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