Spin Response in Organic Semiconductors with Tuned Spin-Orbit Coupling

该项目由材料研究部的电子和光子材料（Electronic and Photonic Materials，简称EMPs）和凝聚态物理（Condensed Matter Physics，简称CMP）项目共同资助。非技术描述：该项目是关于新合成的有机聚合物的物理性质，这些聚合物在聚合物链的沿着不同间隔处含有铂（Pt）原子。链内Pt原子显著增强了聚合物链中电子的自旋和轨道角动量之间的耦合。这导致了强的红色磷光发射，除了已知的蓝色荧光发射从更常见的聚合物链没有自旋轨道耦合。这两种类型的发射机制的结合产生了白色光，可以在新开发的白色有机发光二极管中使用，这可能在未来取代常规灯泡。通过对这些聚合物的光学、电学和磁学研究，探索了一些基础科学问题，这些问题可能对这些材料的潜在应用产生重要影响。此外，在主要研究人员的研究小组内整合大量的实验技术，可以有效地教育参与这个高度跨学科研究项目的研究生和本科生。该项目的教育方面特别开放与犹他州大学理学院的ACESS计划合作，该计划旨在提高妇女对自然科学的参与。技术说明：本研究项目是研究新合成的具有大自旋轨道耦合的π共轭聚合物中的自旋泵送、自旋注入和自旋操纵所揭示的自旋对准载流子响应。在这些聚合物中，Pt原子沿链以不同的间隔沿着插入到有机结构单元中，这有效地调节了聚合物的自旋轨道耦合。该研究使用了各种新颖的光学，磁光和电学测量技术。利用铁磁电极自旋注入、铁磁衬底自旋波自旋泵浦和圆偏振光吸收光学自旋取向三种有效的自旋极化技术，对铂聚合物中的自旋取向载流子进行极化。以下过程进行了研究：自旋取向的载流子注入和输运在这些聚合物中使用的磁光克尔效应和磁致发光;自旋波泵浦在各种铁磁自旋注入器诱导的自旋电流;和光诱导自旋取向的三重态激子。这些研究有助于理解有机自旋器件中控制自旋响应的物理过程，并有可能彻底改变其性能。

This project is jointly funded by the Electronic and Photonic Materials (EPM) and Condensed Matter Physics (CMP) Programs, both in the Division of Materials Research. Non-technical Description: This project is on the physical properties of newly synthesized organic polymers that contain platinum (Pt) atoms at different intervals along the polymer chain. The intrachain Pt atoms substantially enhance the coupling between the spin and the orbital angular momentum of electrons in the polymer chain. This leads to a strong red phosphorescence emission, in addition to the blue fluorescence emission known from more common polymer chains without spin-orbit coupling. The combination of both types of emission mechanisms creates white light that can serve in newly developed white organic light emitting diodes, which may replace regular bulbs in the future. Through optical, electrical and magnetic studies of these polymers, a number of fundamental scientific questions are explored that can have important ramifications on potential applications of these materials. In addition, the integration of the large arsenal of experimental techniques within the research groups of the principal investigators serves to efficiently educate graduate and undergraduate students involved in this highly interdisciplinary research project. The educational aspects of this project are in particular open to collaboration with the ACESS program at College of Science of the University of Utah, which aims to enhance the involvement of women in natural sciences.Technical Description: This research project is to study the spin-aligned carrier response as revealed by spin-pumping, spin-injection and spin-manipulation in newly synthesized pi-conjugated polymers with large spin-orbit coupling. In these polymers, Pt atoms are inserted into the organic building blocks at different intervals along the chain, which effectively tune the polymer spin-orbit coupling. The research uses a variety of novel optical, magneto-optical and electrical measurement techniques. The spin aligned carriers in Pt-polymers are polarized using the three effective techniques of spin polarization that include: spin injection by ferromagnetic electrodes, spin pumping by spin-waves in ferromagnetic substrates, and optical spin alignment by circularly polarized light absorption. The following processes are investigated: spin aligned carrier injection and transport in these polymers using the magneto-optic Kerr effect and magneto-electroluminescence; spin-current induced by spin-wave pumping in various ferromagnetic spin injectors; and photo-induced spin aligned triplet excitons. These studies contribute to the understanding of the physical processes that govern the spin response in organic spin devices, and have the potential to revolutionize their performance.