| Autor: |
Okazawa, A., Yoshida, J., Kida, N., Kashima, I., Murata, W., Enomoto, M., Kojima, N. |
| Předmět: |
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| Zdroj: |
Hyperfine Interactions; Apr2014, Vol. 226 Issue 1-3, p351-357, 7p |
| Abstrakt: |
We have investigated magnetic properties in a series of photoresponsive dithiooxalato (dto)-bridged iron mixed-valence complexes, (SP-R)[FeFe(dto)] (SP-R = R-substituted pyridospiropyran cation; R = Me, Et, and Pr; abbreviated as 1, 1, and 1, respectively). As for our previous reports, 1 and 1 show two-step succeeding ferromagnetic transitions at T = 25 & 8 K and 22 & 5 K, respectively. However, 1 has no hysteresis in the magnetic susceptibility, while 1 undergoes the charge transfer phase transition with thermal hysteresis around 75 K. To elucidate the two-step transitions of them, we measured Fe Mössbauer spectra of 1. The spectra of Fe ( S = 2) and Fe ( S = 1/2) in the HTP were observed in the magnetically ordered state as well as the paramagnetic state, and revealed that only HTP exists in a temperature range up to 5 K. The result is consistent with that of 1, where one ferromagnetic phase transition occurs at T = 10 K. Fe Mössbauer spectroscopy is useful to clarify the origin of the succeeding magnetic transition for these systems. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
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