Tuning of spin-orbit coupling in metal-free conjugated polymers by structural conformation

Eric Vetter, Ian VonWald, Shijia Yang, Liang Yan, Sanaz Koohfar, Divine Kumah, Zhi-Gang Yu, Wei You, and Dali Sun
Phys. Rev. Materials 4, 085603 – Published 28 August 2020
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Abstract

Manipulating spin-orbit coupling (SOC) is a key achievement for spin-orbitronic applications since SOC determines spin-diffusion lengths and spin-to-charge conversion efficiencies. While in most organic semiconductors SOC is inherently very weak due to being composed of primarily light elements, the SOC in conjugated polymer systems is also intimately tied to the polymer's structural conformation and thus may be manipulated. Here we report a modification of SOC in conjugated polymers by altering torsion angle between conjugated units. Spin-pumping experiments are performed on three poly(3-alkylthiophene) polymer films with decreasing conjugation lengths and concomitantly increasing torsion angle. The more twisted polymer exhibits a shorter spin-diffusion length and a giant spin-mixing conductance (up to 1021m2 ), which is attributed to an increased SOC by structural conformation. This work offers a route for enhancing SOC and spin-injection efficiency in organic materials for spintronic applications.

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  • Received 6 January 2020
  • Accepted 31 July 2020

DOI:https://doi.org/10.1103/PhysRevMaterials.4.085603

©2020 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied PhysicsPolymers & Soft Matter

Authors & Affiliations

Eric Vetter1,3, Ian VonWald2, Shijia Yang1, Liang Yan2, Sanaz Koohfar1, Divine Kumah1, Zhi-Gang Yu4,5, Wei You2,6,*, and Dali Sun1,6,†

  • 1Department of Physics, North Carolina State University, Raleigh, North Carolina 27695, USA
  • 2Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
  • 3Department of Material Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695, USA
  • 4ISP/Applied Sciences Laboratory, Washington State University, Spokane, Washington 99202, USA
  • 5Department of Physics and Astronomy, Washington State University, Pullman, Washington 99164, USA
  • 6Organic and Carbon Electronics Lab (ORaCEL), North Carolina State University, Raleigh, North Carolina 27695, USA

  • *wyou@unc.edu
  • dsun4@ncsu.edu

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Issue

Vol. 4, Iss. 8 — August 2020

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