On surface spin tuning in single molecule magnets

对单个分子的自旋态进行可控操纵是材料科学和纳米级新型电子器件开发的最终目标之一。基于分子的自旋电子单元有望拥有全新的特性，并且还通过自组装以及通过化学合成定制基本特性来提供成本效益高的制造优势。分子纳米磁体，代表介观系统的磁双稳性和通用的量子行为，是特别感兴趣的应用领域中的自旋为基础的数据存储和量子计算。该项目的主要思想是研究单个单分子磁体（SMM）复合物表面的结构，电子和磁性，以及通过电子供体和受体的化学掺杂或通过使用STM几何形状内的背栅电极的外部电场来可控地操纵它们的基本性质。一个特别的重点是把可控地调整的磁性SMM的可能性。尽管最近在合成和表面沉积的SMMs的进展，控制表面上的SMMs的磁双稳态的因素仍然不清楚。这部分是由于足够坚固以承受表面沉积的有限数量的SMM，以及由于缺乏可靠的协议，该协议允许对表面上的SMM的电子性质和磁性进行可控的调谐。在该项目的框架中，我们实施了沉积方法和调查技术的独特组合，旨在缩小这一差距，并揭示功能衬底上定义明确的吸附单分子磁体的电子状态和自旋特性的详细见解，以及调整它们的电子特性以可控地修改它们的磁性行为。最终目标将是在STM结内使用亚分子分辨率和门控可能性，以便调整单个SMM复合物的电子和磁性，这将为现实电子器件中分子纳米磁体的行为提供更深入的了解。

Controlled manipulation of the spin states of individual molecules is one of the ultimate goals in materials science and the development of novel electronic devices at the nanoscale. Molecule-based spintronic units promise to possess fundamentally new properties and also offer the advantages of cost-effective fabrication through self-assembly as well as through tailoring fundamental properties by chemical synthesis. Molecular nanomagnets, representing mesoscopic systems with magnetic bistability and versatile quantum behavior, are of particular interest for applications in the fields of spin-based data storage and quantum computation. The main idea of this project is to investigate the structural, electronic and magnetic properties of individual single molecule magnet (SMM) complexes at surfaces as well as to controllably manipulate their fundamental properties by either chemical doping with electron donors and acceptors or by external electric fields using a back-gate electrode within the STM geometry. A special focus is put on the possibility to controllably tune the magnetic properties of SMMs. Despite the recent progress in the synthesis and surface deposition of SMMs, the factors controlling magnetic bistability of SMMs on surfaces remain still unclear. This is in part due to the limited number of SMMs robust enough to withstand the surface deposition as well as due to the absence of reliable protocols which allow for controllable tuning of electronic properties and magnetism of SMMs on surfaces. In the frame of this project, we implement a unique combination of deposition methods and investigation techniques aiming to close this gap and to reveal detailed insight in electronic states and spin properties of well-defined adsorbed single molecular magnets on functional substrates as well as to tune their electronic properties to controllably modify their magnetic behavior. The ultimate goal will be to use submolecular resolution and gating-possibilities within the STM junction in order to tune the electronic and magnetic properties of an individual SMM complex which will provide a deeper insight into the behavior of molecular nanomagnets in realistic electronic devices.