Spin Polarization Spectroscopy in Organic Semiconductors

University Of Utah, Salt Lake City UT

Investigators

Abstract

Nontechnical description: As the miniaturization of electronic circuits approaches its limitation, there is a need to find alternative ways to generate, manipulate, transfer and detect information while reducing the energy needed for such operations. One approach to achieve this is to use the magnetic behavior of electrons, otherwise known as spin. Using the spin in order to implement such a new type of information processing is called "spintronics". The research in this project focuses on studying physical mechanisms that allow for spintronics in carbon-based, so-called organic semiconductors. These studies include in particular the control and manipulation, the transport and the very sensitive detection of magnetic phenomena in thin plastic films. Spintronics devices based on such novel materials are engineered, fabricated and tested using electrical, magnetic and optical measurements. In addition, the integration of the large arsenal of experimental efforts serves to efficiently educate graduate and undergraduate students participating in these interdisciplinary research projects. Separately, the research team is also reaching out to pre-college students in order to inform them on career opportunities and the technological potential of the Physical and Natural Sciences. Technical description: The goal of this project is to improve the understanding of electron spin polarization effects in organic semiconductors with tunable strength of the spin-orbit coupling. Specifically, the project aims to develop an understanding of the physical nature of spin transport in this materials class. The research is focused on spin polarized charge carrier ensembles using two spin-polarization techniques: (i) spin-pumping by resonantly generated spin-waves in ferromagnetic substrates, which is detected by the inverse spin-Hall effect; and (ii) thermally induced equilibrium spin-polarization obtained from high magnetic fields at cryogenic temperatures, which is detected by field-induced circular polarization emission. Spintronics devices such as spin-valves, spin-diodes, and spin organic light emitting diodes are engineered, fabricated and tested using electrical, magnetic and optical means. This project integrates the University of Utah's large arsenal of experimental capabilities, including polymer and small molecule deposition, magneto-transport, electrically-detected ferromagnetic resonance, magnon-related spin-pumping, modeling as well as device fabrication, processing and testing. Together, these unfold the broad impact of an entirely new class of electronics for educating a cadre of graduate and undergraduate students who are involved in the execution of this project, and the outreach that is made to local High School and Middle School communities.