Pressure effects on an organic radical ferromagnet: 2,5-difluorophenyl-a-nitronyl nitroxide
スポンサーリンク
概要
- 論文の詳細を見る
Raising a transition temperature (Tc) in organic radical ferromagnets is a desire for material scientists. We investigated the pressure effects on an organic radical ferromagnet 2,5-difluorophenyl-ﾎｱ-nitronyl nitroxide (2,5-DFPNN), which has a ferromagnetic transition at 0.45 K. The hydrostatic pressure effects were investigated through measurements of ac magnetic susceptibility (ﾏ・ up to P=1.7 GPa, heat capacity (Cp) up to P=1.5 GPa, and powder x-ray diffraction up to P=4.7 GPa. Furthermore, ac magnetic susceptibility under nonhydrostatic pressure was also measured in the pressure region up to 10.0 GPa. As for 2,5-DFPNN, we observed the pressure-induced enhancement of Tc as dTc/dP=7.9ﾃ・0-2 K/GPa [Tc(P=1.5 GPa)=0.57 K], while other prototypes, the ﾎｲ phase of p-NPNN and p-Cl-C6H4-CH=N-TEMPO show the negative pressure effects. The results for the Cp and the crystal structural analysis suggest that the magnetic dimension of the short-range order developing above Tc transforms from one dimension (a axis) to two dimensions (ac plane) under high pressure. This increase of the magnetic dimension probably promotes to increase Tc. The ferromagnetic signal of ﾏ・ however, decreases with increasing pressure, and finally disappears for P>~5.0 GPa. The decrease seems to originate from the decrease of the ferromagnetic interaction along the b axis. Similar instability of organic ferromagnetic long range order against pressure has been observed for the ﾎｲ phase of p-NPNN and p-Cl-C6H4-CH=N-TEMPO.
論文 | ランダム
- 遺伝的胸椎前弯・前側弯ウサギ (Lordoscoliotic Rabbit) における脊柱変形のX線学的, 組織学的検討
- イスラムビジネスにチャンスあり!--近くて遠い11億人市場
- 宗教学的宗教哲学の試み--イスラームの宗教性 ([宗教哲学会]第二回学術大会) -- (シンポジウム 宗教哲学の多様性)
- ネットが巻き起こしたイスラム革命の潮流
- イスラム金融の最新事情と展望