We report measurements of room-temperature spin-relaxation times T1 and T2 of charge-carrier spins in a π-conjugated polymer thin film under bipolar injection and low (1\mboxmT≲B0≲10\mboxmT) static magnetic fields, using electrically detected magnetic resonant Hahn-echo and inversion-recovery pulse sequences. The experiments confirm the correlation between the magnetic-field sensitive observables of radical-pair processes, which include both the spin-dependent recombination currents in organic semiconductors and the associated spin-relaxation times when random local hyperfine fields and external magnetic fields compete in magnitude. Whereas a striking field dependence of spin-lattice relaxation exists in the low-field regime, the apparent spin decoherence time remains field independent as the distinction between the two is lifted at low fields.
@article{arxiv.2207.07086,
title = {Spin relaxation dynamics of radical-pair processes at low magnetic fields},
author = {T. H. Tennahewa and S. Hosseinzadeh and S. I. Atwood and H. Popli and H. Malissa and J. M. Lupton and C. Boehme},
journal= {arXiv preprint arXiv:2207.07086},
year = {2024}
}