Dynamics and Supramolecular Organization of the 1D Spin Transition Polymeric Chain Compound [Fe(NH2trz)3](NO3)2. Muon Spin Relaxation

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• 作者：Yann Garcia ; Stewart J. Campbell ; James S. Lord ; Yves Boland ; Vadim Ksenofontov ; Philipp G&uuml ; tlich
• 刊名：Journal of Physical Chemistry B
• 出版年：2007
• 出版时间：September 27, 2007
• 年：2007
• 卷：111
• 期：38
• 页码：G&uumltlich
• 全文大小：218K
• 年卷期：v.111,no.38(September 27, 2007)
• ISSN：1520-5207

文摘

The thermal spin transition that occurs in the polymeric chain compound [Fe(NH₂trz)₃](NO₃)₂ above roomtemperature has been investigated by zero-field muon spin relaxation (SR) over the temperature range ~8-402 K. The depolarization curves are best described by a Lorentzian and a Gaussian line that represent fastand slow components, respectively. The spin transition is associated with a hysteresis loop of width T = 34K (T_1/2 = 346 K and T_1/2 = 312 K) that has been delineated by the temperature variation of the initialasymmetry parameter, in good agreement with previously published magnetic measurements. Zero-field andapplied field (20-2000 Oe) SR measurements show the presence of diamagnetic muon species andparamagnetic muonium radical species (A = 753 ± 77 MHz) over the entire temperature range. Fast dynamicshave been revealed in the high-spin state of [Fe(NH₂trz)₃](NO₃)₂ with the presence of a Gaussian relaxationmode that is mostly due to the dipolar interaction with static nuclear moments. This situation, where themuonium radicals are totally decoupled and not able to sense paramagnetic fluctuations, implies that thehigh-spin dynamics fall outside the muon time scale. Insights to the origin of the cooperative effects associatedwith the spin transition of [Fe(NH₂trz)₃](NO₃)₂ through muon implantation are presented.