TY - JOUR
T1 - Quantum dynamics of nuclear spins and spin relaxation in organic semiconductors
AU - Mkhitaryan, V. V.
AU - Dobrovitski, V. V.
PY - 2017
Y1 - 2017
N2 - 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 modeled utilizing 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/t. Based on the numerical results, we devise a simple formula describing the effect quantitatively.
AB - 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 modeled utilizing 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/t. Based on the numerical results, we devise a simple formula describing the effect quantitatively.
UR - http://resolver.tudelft.nl/uuid:c4865b35-4b47-44b6-931e-5d283e1819e0
UR - http://www.scopus.com/inward/record.url?scp=85023781685&partnerID=8YFLogxK
U2 - 10.1103/PhysRevB.95.214204
DO - 10.1103/PhysRevB.95.214204
M3 - Article
AN - SCOPUS:85023781685
SN - 1098-0121
VL - 95
JO - Physical Review B (Condensed Matter and Materials Physics)
JF - Physical Review B (Condensed Matter and Materials Physics)
IS - 21
M1 - 214204
ER -