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Departmental Colloquium

Title
Current Advances in Spinterface and Spin Transport in Organic Spin Valves  
Guest Speaker
Professor Tho Nguyen  
Guest Affiliation
UGA Physics and Astronomy  
Guest Affiliation Url
https://www.physast.uga.edu/research/nguyen  
When
Thursday, January 11, 2018 3:30 pm - 4:30 pm  
Location
Physics Auditorium (Rm 202)  
Details

Organic spin valves (OSVs), which are comprised of an organic spacer sandwiched between two ferromagnetic (FM) electrodes, have attracted great attention from scientific community in the past 16 years. Such spin valve structures using inorganic spacers have revolutionized magnetic memory and sensor application. Magnetoresistance (MR) response in OSVs generally relies on the spin injection/detection at the FM/organic interface (dubbed spinterface), and the spin diffusion length in the organic spacer. Organic semiconductors (OSEC) possess weak hyperfine interaction and spin-orbit coupling, and hence long spin lifetime. The spin transport is due to π-orbital electrons in OSECs which are comprised of light-weight elements such as hydrogen and carbon. Therefore, they have been thought to possess considerably long spin diffusion length, suitable for obtaining larger MR in OSVs. However, in conventional OSVs, the interface between the organic and FM electrodes, and the structural order of the organic interlayer are poorly controlled because epitaxial growth is not possible for OSECs. Therefore, the spinterface effect and spin transport in these devices are complicated, and their complete understanding has remained elusive. In this talk, I will discuss the current advanced studies in our group for understanding and manipulating the spinterface effect and spin transport in OSVs. In particular, for the spin transport, we will show the statistical origin of the hyperfine interaction strength and the existence of curvature induced spin-orbit coupling in OSECs. For the spin injection/detection, we will present several methods to manipulate the spinterface effect. These include the use of self-assembled monolayers (SAM) at the interface, an organic ferroelectric insulator for the spacer, and organic/FM/organic triple layers for the spacer.

 

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