Studies of a Large Odd-Numbered Odd-Electron Metal Ring: Inelastic Neutron Scattering and Muon Spin Relaxation Spectroscopy of Cr8 Mn.
Studies of a Large Odd-Numbered Odd-Electron Metal Ring: Inelastic Neutron Scattering and Muon Spin Relaxation Spectroscopy of Cr8 Mn.
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DOI：
10.1002/chem.201503431
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发表时间：
2016-01-26
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影响因子：
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通讯作者：
Winpenny RE
中科院分区：
文献类型：
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作者：
Baker ML;Lancaster T;Chiesa A;Amoretti G;Baker PJ;Barker C;Blundell SJ;Carretta S;Collison D;Güdel HU;Guidi T;McInnes EJ;Möller JS;Mutka H;Ollivier J;Pratt FL;Santini P;Tuna F;Tregenna-Piggott PL;Vitorica-Yrezabal IJ;Timco GA;Winpenny RE
研究了九元反铁磁（AF）分子纳米磁体Cr 8 Mn的自旋动力学. Cr 8 Mn是一个罕见的大的奇数元AF环的例子，并且具有奇数个3d电子存在。奇数元AF环是不寻常的，并且由于存在竞争交换相互作用而引起兴趣，从而导致受抑自旋基态。报道了两种Cr 8 Mn变体的化学合成和结构，这两种变体的不同之处仅在于它们的晶体堆积。利用非弹性中子散射（INS）和μ子自旋弛豫谱（μSR）研究了自旋阻挫的证据。从INS研究中，我们准确地确定了一个适当的微观自旋哈密顿量，我们表明μSR对Cr 8 Mn中S=1/2到S=3/2的基态自旋交叉敏感。μ子不对称共振的估计宽度与避免交叉的存在是一致的。通过对自旋对相关和标量自旋手征的分析，对基态内部自旋结构的研究显示了一种非共线的自旋结构，这种结构在相反手征的非平面态之间波动。
The spin dynamics of Cr8Mn, a nine‐membered antiferromagnetic (AF) molecular nanomagnet, are investigated. Cr8Mn is a rare example of a large odd‐membered AF ring, and has an odd‐number of 3d‐electrons present. Odd‐membered AF rings are unusual and of interest due to the presence of competing exchange interactions that result in frustrated‐spin ground states. The chemical synthesis and structures of two Cr8Mn variants that differ only in their crystal packing are reported. Evidence of spin frustration is investigated by inelastic neutron scattering (INS) and muon spin relaxation spectroscopy (μSR). From INS studies we accurately determine an appropriate microscopic spin Hamiltonian and we show that μSR is sensitive to the ground‐spin‐state crossing from S=1/2 to S=3/2 in Cr8Mn. The estimated width of the muon asymmetry resonance is consistent with the presence of an avoided crossing. The investigation of the internal spin structure of the ground state, through the analysis of spin‐pair correlations and scalar‐spin chirality, shows a non‐collinear spin structure that fluctuates between non‐planar states of opposite chiralities.