The Effect of High Pressure on Single Molecule Magnets

磁性材料用于广泛的应用，包括信息存储设备，其中信息由金属氧化物或合金的磁性颗粒存储。有一种驱动器可以制造具有越来越小的颗粒的设备，以便增加可以存储在给定大小的磁盘驱动器或磁带长度上的信息量。某些过渡金属络合物存在，它由一个核心组成，该核心包含由配体分子衍生的氧原子和氮原子连接的金属离子。其中一些化合物属于一类被称为单分子磁铁的分子。单分子磁体的行为就像是包裹在有机配体鞘中的非常小的金属氧化物碎片。这些碎片比目前用于信息存储的氧化物颗粒小得多，因此它们可以代表一种实现尽可能高密度的信息存储的手段。每个分子代表一比特的信息：一种磁态可能代表二进制0，另一种可能代表二进制1。单分子磁体的基本性质是引起强烈科学兴趣的主题。它们强烈地依赖于用于形成络合物的金属离子的性质、离子之间的距离以及连接金属中心的配体原子处的角度。在以前的工作中，我们已经证明，通过施加1-100kbar的压力，即大约1000-100000倍的大气压，可以改变原子间的几何结构。这些压力可以通过在两个钻石钉子之间的装置中压缩样品来实现，这种装置可以很容易地放在一个人的手掌中。我们还可以通过X射线结晶学来确定单分子磁体的结构，并测量它们的磁性能，当它们处于金刚石压腔内的高压状态时。因此，我们可以以一种非常可控和系统的方式，探索几何结构变化对给定络合物结构和磁性的影响。这些实验将是独一无二的，任何地方的其他合作团队都没有组合的专业知识来制造单分子磁体，建立合适的高压室，并在高压下研究络合物的结构和磁性。我们将从研究高压对一些简单的络合物和一些著名的单分子磁体的影响开始，为新分子的研究做准备。这项研究的结果不仅具有重大的基础性意义，使磁性的变化与结构的变化密切相关，而且还可能揭示将磁性不活跃的分子转化为单分子磁体所必需的结构变化。

Magnetic materials are used in a broad range of applications, including devices for information storage, in which information is stored by magnetic particles of metal oxide or alloys. There is a drive to make devices with ever-smaller particles in order to increase the amount of information that can be stored on a given size of disk-drive or length of magnetic tape. Certain transition metal complexes exist which consist of a core containing metal ions connected by oxygen and nitrogen atoms derived from ligand molecules. Some of these complexes fall into a class of molecules called Single Molecule Magnets. Single molecule magnets behave as though they are very small fragments of metal oxide encapsulated within a sheath of organic ligands. These fragments are much smaller than the oxide particles currently used in information storage, and therefore they could represent a means of achieving the highest possible density of information storage. Each molecule would represent a single bit of information: one magnetic state might represent a binary 0, the alternative a binary 1.The fundamental properties of single molecule magnets are the subject of intense scientific interest. They are strongly dependent on the nature of the metal ions used to form the complex, the distances between the ions, and the angles subtended at the ligand atoms which link the metal centres together. In previous work, we have shown that interatomic geometry can be altered by applying pressures of 1 - 100 kbar, that is about 1000 to 100 000 times atmospheric pressure. These pressures are achievable by compressing a sample between two diamond anvils in devices which would fit readily into the palm of one's hand. We can also determine the structures of the single molecule magnets by X-ray crystallography, and measure their magnetic properties, while they are at high pressure inside the diamond anvil cell. We can therefore probe, in a very controlled and systematic way, the effect that changes in geometry have on structural and magnetic properties of a given complex.These experiments will be unique, no other collaborative team anywhere has the combined expertise to make single molecule magnets, build suitable high pressure cells and investigate the structures and magnetic properties of the complexes at high pressure. We will begin by investigating the effect of high pressure on some simple complexes and on some well-known single molecule magnets, building up towards investigations of new molecules. The results of this research will not only be of great fundamental interest, enabling changes in magnetic properties to be closely correlated with structural changes, but they may also reveal the structural changes necessary to convert magnetically inactive molecules into single molecule magnets.