Field-induced slow relaxation of magnetization in a tetrahedral Co(II) complex with easy plane anisotropy
Field-induced slow relaxation of magnetization in a tetrahedral Co(II) complex with easy plane anisotropy
复制标题
具有易平面各向异性的四面体 Co(II) 配合物中场致磁化缓慢弛豫
DOI：
10.1039/c3dt51801a
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发表时间：
2013-01-01
影响因子：
4
通讯作者：
Duan, Chunying
中科院分区：
文献类型：
--
作者：
Huang, Wei;Liu, Tao;Duan, Chunying
获得了单核 Co(II) 配合物 dmphCoBr（dmph = 2,9-二甲基-1,10-菲咯啉），并在 X 射线结构上表征为扭曲的四面体环境，该环境是高自旋 Co(II) 具有中等强度的正各向异性的原因。结合低温下的变场磁化率数据，高场电子顺磁共振 (HF-EPR) 光谱揭示了复杂的 dmphCoBr 中存在易平面各向异性 (D > 0)。在直流磁场存在下，观察到 dmphCoBr 的慢磁弛豫效应。在非常低的温度下，交流磁化率数据显示磁弛豫时间 tau 与温度无关，而高于 2.4 K 时，热激活阿伦尼乌斯行为以 U-eff = 22.8(8) cm(-1) 和 tau(0) = 3.7(5) x 10(-10) s 为主。在同晶化合物 dmphZnBr 基质内稀释复合物后，交流磁化率数据揭示了慢磁弛豫的单个分子性质，并表明在低温下观察到的量子隧道路径可能是由分子间偶极相互作用介导的。
The mononuclear Co(II) complex dmphCoBr (dmph = 2,9-dimethyl-1,10-phenanthroline) was obtained and X-ray structurally characterized as a distorted tetrahedron environment that is responsible for the moderately strong positive anisotropy of high spin Co(II). In combination with variable-field magnetic susceptibility data at low temperature, high-field electron paramagnetic resonance (HF-EPR) spectroscopy reveals the presence of easy-plane anisotropy (D > 0) in complex dmphCoBr. Slow magnetic relaxation effects were observed for dmphCoBr in the presence of a dc magnetic field. At very low temperatures, ac magnetic susceptibility data show the magnetic relaxation time, tau, to be temperature-independent, while above 2.4 K thermally activated Arrhenius behavior is dominated with U-eff = 22.8(8) cm(-1) and tau(0) = 3.7(5) x 10(-10) s. Upon dilution of the complex within a matrix of the isomorphous compound dmphZnBr, ac susceptibility data reveal the individual molecular nature of the slow magnetic relaxation and indicate that the quantum tunneling pathway observed at low temperatures is likely mediated by intermolecular dipolar interactions.