Nanomagnets with high molecular symmetry: ground state spin, anisotropy and macroscopic quantum tunneling

具有高分子对称性的纳米磁体：基态自旋、各向异性和宏观量子隧道

• 批准号: 5368291
• 负责人: Professor Dr. Paul Müller (†)
• 金额: --
• 依托单位: Lehrstuhl für Experimentalphysik
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2002
• 资助国家: 德国
• 起止时间: 2001-12-31 至 2008-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/5368291?language=en
• 关键词: Nanomagnets; molecular; symmetry; ground; state

The ultimate goal in the area of single molecule magnets (SMM) is to create molecules with blocking temperatures larger than room temperature. This would allow applications like e.g. molecular storage devices. This project aims to approach this goal in two ways. First, the physical laws controlling the effectiveness of the SMM behavior shall be explored in order to identify the key properties which have to be optimized with respect to large blocking temperatures. We will investigate the family of molecular ferric stars MeFe3L6 with Me = Fe, Cr, Al. For FeFe3L6 and CrFe3L6, the phenomenon of macroscopic quantum tunneling (MQT) associated with SMM behavior shall be investigated by torque measurements at temperatures of 0.25 K applying fast magnetic field sweeps. Since the three members of this family have essentially identical geometrical structures a comparison of their properties will allow deep insights into the mechanism of MQT. The magnetic anisotropy is already known to play an important role for SMM behavior. Thus, a second aim of this project is to study the relationship between geometrical structure and magnetic anisotropy of molecular clusters in order to find rules which will help chemists to create molecular systems with high blocking temperatures. Here we will focus on the complexes MeFe3L6 but also on a Mn[3x3]-grid. Due to their high molecular symmetries, they represent ideal model systems to address this question. Experimentally, magnetic anisotropy will be investigated by high-field torque magnetometry and high-field EPR spectroscopy at 17-26 GHz.

单分子磁体（SMM）领域的最终目标是创造出阻挡温度大于室温的分子。这将允许例如分子存储设备的应用。本项目旨在通过两种方式实现这一目标。首先，应探索控制SMM行为有效性的物理定律，以确定必须针对大阻塞温度进行优化的关键属性。我们将研究分子铁星MeFe 3L 6（Me = Fe，Cr，Al）族，对于FeFe 3L 6和CrFe 3L 6，将通过在0.25K温度下施加快速磁场扫描的扭矩测量来研究与SMM行为相关的宏观量子隧穿（MQT）现象。由于这个家族的三个成员具有基本上相同的几何结构，因此比较它们的性质将使我们能够深入了解MQT的机制。磁各向异性对SMM行为起着重要的作用。因此，该项目的第二个目的是研究分子团簇的几何结构和磁各向异性之间的关系，以找到有助于化学家创建具有高阻断温度的分子系统的规则。在这里，我们将重点关注络合物MeFe 3L 6，但也关注Mn[3x 3]-网格。由于它们的高分子对称性，它们代表了解决这个问题的理想模型系统。在实验上，磁各向异性将在17-26 GHz的高场转矩磁力仪和高场EPR光谱研究。