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首页> 外文期刊>Polyhedron: The International Journal for Inorganic and Organometallic Chemistry >Quantum fluctuations and long-range order in molecular magnets
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Quantum fluctuations and long-range order in molecular magnets

机译：分子磁体中的量子涨落和远距离有序

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We review our studies of the effect of transverse fields on the susceptibility and magnetization of single crystals of the prototype single molecule magnet (SMM), Mn_(12)-acetate, and of a new high-symmetry variant, Mn_(12)-acetate-MeOH. SMM single crystals can exhibit long range ferromagnetic order associated with intermolecular dipole interactions. Transverse fields increase quantum spin fluctuation and quantum tunneling of the magnetization suppressing long range order. However, we have found that suppression of the Curie temperature by a transverse field in Mn _(12)-acetate is far more rapid than predicted by the Transverse-Field Ising Ferromagnetic Model (TFIFM). It appears that solvent disorder in Mn _(12)-acetate that results in an intrinsic distribution of small discrete tilts of the molecular magnetic easy axis from the global easy axis of the crystal (≈±1) gives rise to a distribution of random-fields that further suppresses long-range order. Semiquantitative agreement with the predictions of a Random-Field Ising Ferromagnet Model is found. Subsequent susceptibility studies we have conducted of the high symmetry Mn_(12) variant, Mn_(12)-acetate-MeOH, with the same spin structure and similar lattice constants but without the same solvent disorder as Mn _(12)-acetate, agrees with the TFIFM. An important implication of our studies is that long-range order in these two chemically very similar SMMs are described by distinct physical models.
机译：我们回顾了我们对横向磁场对原型单分子磁体（SMM）Mn_（12）-乙酸盐和新的高对称性变量Mn_（12）-乙酸盐单晶磁化率和磁化强度的影响的研究。 -MeOH。 SMM单晶可以表现出与分子间偶极相互作用相关的远距离铁磁有序。横向场增加了量子自旋涨落和磁化的量子隧穿，从而抑制了远距离有序。但是，我们发现，通过Mn _（12）-乙酸盐中的横向磁场抑制居里温度要比通过横向场伊辛铁磁模型（TFIFM）预测的快得多。看来，Mn _（12）-乙酸盐中的溶剂紊乱导致分子磁易轴从晶体的整体易轴（≈±1）的小的离散倾斜的固有分布引起了随机晶体的分布。进一步抑制远程顺序的字段。发现了与随机场伊辛铁磁体模型的预测值的半定量一致性。我们随后对高对称性Mn_（12）变体Mn_（12）-乙酸盐-MeOH进行了敏感性研究，该研究具有相同的自旋结构和相似的晶格常数，但没有与Mn _（12）-乙酸盐相同的溶剂无序性。与TFIFM。我们研究的重要意义在于，这两个化学上非常相似的SMM的远距离顺序由不同的物理模型描述。

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