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Quantum dynamics of nuclear spins and spin relaxation in organic semiconductors

TitleQuantum dynamics of nuclear spins and spin relaxation in organic semiconductors
Publication TypeJournal Article
Year of Publication2017
AuthorsMkhitaryan, VV, Dobrovitski, VV
JournalPhysical Review B
Volume95
Pagination'
Date Published06
Type of ArticleArticle
ISBN Number2469-9950
Accession NumberWOS:000403069600002
Keywordsphysics, spintronics, systems
Abstract

We investigate the role of the nuclear-spin quantum dynamics in hyperfine-induced spin relaxation of hopping carriers in organic semiconductors. The fast-hopping regime, when the carrier spin does not rotate much between subsequent hops, is typical for organic semiconductors possessing long spin coherence times. We consider this regime and focus on a carrier random-walk diffusion in one dimension, where the effect of the nuclear-spin dynamics is expected to be the strongest. Exact numerical simulations of spin systems with up to 25 nuclear spins are performed using the Suzuki-Trotter decomposition of the evolution operator. Larger nuclear-spin systems are modeledutilizing the spin-coherent state P-representation approach developed earlier. We find that the nuclear-spin dynamics strongly influences the carrier spin relaxation at long times. If the random walk is restricted to a small area, it leads to the quenching of carrier spin polarization at a nonzero value at long times. If the random walk is unrestricted, the carrier spin polarization acquires a long-time tail, decaying as 1/root t. Based on the numerical results, we devise a simple formula describing the effect quantitatively.

DOI10.1103/PhysRevB.95.214204
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Photonics