Magnetic property of neptunyl (+2) complex NpO$$_{2}$$(C$$_{6}$$H$$_{7}$$O$$_{2}$$)$$_{2}$$(C$$_{5}$$H$$_{5}$$N)
中村 彰夫; 中田 正美; 中本 忠宏*; 北澤 孝史*; 竹田 満洲男*
Nakamura, Akio; Nakada, Masami; Nakamoto, Tadahiro*; Kitazawa, Takafumi*; Takeda, Masuo*
Magnetic property of a nitrogen (N)-coordinated neptunyl (+2) (Np(VI)) complex. 1 NpO$$_{2}$$(acac)$$_{2}$$(py) (acac=C$$_{6}$$H$$_{7}$$O$$_{2}$$, py=C$$_{5}$$H$$_{5}$$N) was studied by DC magnetization (M) measurements. While previous $$^{237}$$Np M$"o$ssbauer data of 1 exhibited para magnetic-relaxation spectra similar to other oxo-neptunyls (+1,+2), the DC-$$M$$ data have revealed many strikingly different features of 1 from the latter: first, its reciprocal susceptibility ($$chi$$$$^{-1}$$) vs. $$T$$(K) plots showed a peculiar strongly field ($$H$$)-dependent nonparamagnetic behavior, which suggests the presence of small ferromagnetic component with $$T$$$$_{C}$$$$>$$300 K. In addition, its low-temperature isothermal $$M$$ exhibited anomalous relaxation behavior involving initial over-responsive $$M$$ change and subs equent drift back to its "equilibrium" value ($$M$$$$_{rm eq}$$). Moreover, such $$M$$$$_{rm eq}$$ showed strong perturbation effect from the SQUID-$$M$$ measurement itself. Such novel magnetic features suggest the presence of a largely metastable fluctuating magnetic (spin plus orbital) state in 1 as a collective body of individual Ising-type neptunyl (O=Np=O)$$^{+2}$$ molecular magnets.
使用言語 : English
掲載資料名 : Journal of Magnetism and Magnetic Materials
: 310
: 2, Part2
ページ数 : p.1447 - 1449
発行年月 : 2007/03
出版社名 : Elsevier
発表会議名 : 17th International Conference on Magnetism (ICM 2006)
開催年月 : 2006/08
開催都市 : Kyoto
開催国 : Japan
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受委託・共同研究相手機関 : 東邦大学
登録番号 : BB20061660
抄録集掲載番号 : 35001168
論文投稿番号 : 2755
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