Organic Antiferromagnetic Metals Exhibiting Superconducting Transitions κ-(BETS)2FeX4 (X=Cl, Br): Drastic Effect of Halogen Substitution on the Successive Phase Transitions
✍ Scribed by Takeo Otsuka; Akiko Kobayashi; Yasuhisa Miyamoto; Junji Kiuchi; Sohichiro Nakamura; Nobuo Wada; Emiko Fujiwara; Hideki Fujiwara; Hayao Kobayashi
- Publisher
- Elsevier Science
- Year
- 2001
- Tongue
- English
- Weight
- 411 KB
- Volume
- 159
- Category
- Article
- ISSN
- 0022-4596
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✦ Synopsis
The magnetic and thermal properties of an organic conductor incorporating localized magnetic moments, -(BETS) 2 FeCl 4 , were investigated down to 60+70 mK. Similar to the Br analogue, -(BETS) 2 FeBr 4 , -(BETS) 2 FeCl 4 exhibited successive antiferromagnetic and superconducting transitions with lowering temperature (T N ؍ 0.45 K, T C ؍ 0.1 K). That is, -(BETS) 2 FeCl 4 is the second antiferromagnetic organic metal that exhibits a superconducting transition at ambient pressure. It became clear that the halogen exchange (BrPCl) in the anions results in the strong reduction of both magnetic and superconducting transition temperatures. Resistivities showed a small drop at 0.45 K ( ؍ T N ), which gave a direct evidence of the existence of +d interaction between metal electrons and localized magnetic moments of Fe atoms. In contrast to -(BETS) 2 FeBr 4 exhibiting a three-dimensional nature of the magnetic transition, the speci5c heat of -(BETS) 2 FeCl 4 indicates the low dimensionality of the spin system.