在一个新的[Mn18]2+单分子磁铁中磁化量子道化, s = 13
Euan K Brechin1, Colette Boskovic, Wolfgang Wernsdorfer
1Department of Chemistry, Indiana University, Bloomington, Indiana 47405-7102, USA.
Journal of the American Chemical Society
|August 15, 2002
概括
这项研究报告了一种新型的集群,[Mn18O14(O2CMe) 18(hep) 4(hepH) 2(H2O) 2 (((ClO4) 2 (1),一个单分子磁铁 (SMM),具有迄今为止最大的旋转和最高的核度. 它在低温下表现出磁化 (QTM) 的量子道化.
科学领域:
- 无机化学 无机化学
- 材料科学 材料科学 材料科学
- 磁电化学 磁电化学 磁电化学
背景情况:
- 单分子磁铁 (SMM) 是具有缓慢磁性放松的分子化合物.
- 开发具有很大的自旋值的高核度SMM对于推进分子磁性至关重要.
- 了解结构和磁性特性之间的关系是设计新的SMM的关键.
研究的目的:
- 为了合成和表征一种新的,高核度的团.
- 研究合成集群的磁性特性,重点关注其作为单分子磁体的潜力.
- 在这个综合体中探索磁化量子道化 (QTM) 现象.
主要方法:
- 乙二二 (hepH) 与特定的前体在乙二中发生反应.
- 用X射线结晶学测定复合物的结构[Mn18O14(O2CMe) 18 ((hep) 4 ((hepH) 2 ((H2O) 2)) ((ClO4) 2) (1).
- 可变温度直流 (DC) 和交流电 (AC) 磁性易感度测量,磁化研究和DC磁化衰变分析.
主要成果:
- 隔离2MnII,16MnIII复合体 (1),其中有一个中心单元Mn4O6和两个单元Mn7O9,显示总旋转S = 13.
- 通过AC易感性研究和观察低于1.0K的hysteresis确认单分子磁铁行为的行为.
- 确定14.8cm-1的有效放松屏障 (Ueff),并观察0.25K以下的温度独立放松,表明磁化量子道化 (QTM).
结论:
- 综合体1代表了最大的自旋和最高核度的单分子磁体 (SMM),以展示磁化 (QTM) 的量子道化.
- 这项研究证明了构建具有显著磁性特性的复杂多核集群的可行性.
- 这项工作有助于对分子材料中的磁现象的基本理解和先进磁系统的设计.
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