Spin and Dipole Ordering at Molecular Film Interfaces

在这个由化学系化学结构、动力学和机理B计划以及材料研究部电子和光子材料计划共同资助的项目中，内布拉斯加州大学的Peter A.Dowben教授和印第安纳大学普渡大学印第安纳波利斯大学的郑瑞华教授正在将具有大磁矩的分子与具有大电偶极的分子相结合，创造具有有趣的自旋电子性质的新材料。其目标是实现一种分子系统，其中磁性可以通过外加电场来改变。如果成功，这项研究将使轻量级、高速、低功耗的电子设备能够应用于更广泛的领域。这项研究汇集了化学家、物理学家和材料科学家来制造和表征新材料。学生培训包括本科生和研究生的国际科学经验，参与化学和物理相结合的尖端研究，以及学生学习向非技术受众交流尖端研究的外展活动。在更专业的术语中，分子磁电系统是通过金属-有机化合物的组合实现的，这些化合物展示了配体控制铁电聚合物或两性、强偶极分子的中心金属自旋态(自旋交叉络合物)。一个具体的目标是构建一种薄膜分子磁电系统，其中分子覆盖层的磁性可以通过基态或激发态的外加电场来改变。起始点是铁自旋-交叉络合物与高度偶极的对苯二酚亚胺两性离子的结合。该研究项目将其他自旋交叉络合物与一系列强偶极分子结合在一起。另一个目标包括构建共晶异分子结构，以便等温控制选定分子的磁性低自旋态和高自旋态之间的切换。最终目标是实现电压控制的、基于磁矩的非常小尺寸的设备，同时提供低功耗、千兆赫、非易失性、本地磁电逻辑或存储器操作，延迟时间缩短，功耗大大降低。该项目集中了基础界面化学、异分子界面上的偶极耦合、前沿轨道的建模、已定义的高质量有机多层膜的制备以及外加电场的磁感应特性的研究。

In this project jointly funded by the Chemical Structure, Dynamic & Mechanism B Program of the Chemistry Division and the Electronic and Photonic Materials program of Materials Research division, Professor Peter A. Dowben at the University of Nebraska and Professor Ruihua Cheng at Indiana University Purdue University Indianapolis are combining molecules with large magnetic moments with molecules with large electric dipoles to create new materials with interesting spintronic properties. The goal is to achieve a molecular system where the magnetic properties can be altered by an applied electric field. If successful, the research will enable lightweight, high-speed, low-power electronic devices for a broad range of applications. This research brings together chemists, physicists, and material scientists to make and characterize the new materials. Student training includes international experiences in science for both undergraduate and graduate students, involvement in cutting edge research at the interface of chemistry and physics, and outreach activities where the students learn to communicate cutting edge research to a nontechnical audience. In more technical terms, a molecular magnetoelectric system is achieved by combinations of metal-organic compounds that demonstrate ligand control of the central metal spin state (spin crossover complexes) with ferroelectric polymers or zwitterionic, strongly dipolar molecules. One specific objective is to construct a thin-film molecular magneto-electric system where the magnetic properties of the molecular overlayer are altered by an applied electric field in either the ground state or the excited state. The starting point is the combination of an iron spin-crossover complex with the highly dipolar p-benzoquinonemonoimine zwitterion. The research project grows to include other spin crossover complexes in combination with a wide range of strongly dipolar molecules. Another objective includes the construction of a co-crystal heteromolecular structure in order to isothermally control switching between magnetic low-spin and high-spin states of selected molecules. The ultimate goal is to achieve voltage-controlled, magnetic moment-based devices of very small dimensions while delivering low-power, gigahertz, nonvolatile, local magneto-electric logic or memory operations with diminish latency time and much reduced power consumption. This project brings together investigations of fundamental interface chemistry, dipole coupling at hetero-molecular interfaces, the modeling of frontier orbitals, the fabrication of defined high-quality organic multilayers, and the characterization of magnetic induction with an applied electric field.