Coherent charge transport can occur in organic semiconductor crystals thanks to the highly periodic electrostatic potential—despite the weak van der Waals bonds. And as spin–orbit coupling is usually weak in organic materials, robust spin transport is expected, which is essential if they are to be exploited for spintronic applications. In such systems, momentum relaxation occurs via scattering events, which enables an intrinsic mobility to be defined for band-like charge transport, which is >10 cm2 V−1 s−1. In contrast, there are relatively few experimental studies of the intrinsic spin relaxation for organic band-transport systems. Here, we demonstrate that the intrinsic spin relaxation in organic semiconductors is also caused by scattering events, with much less frequency than the momentum relaxation. Magnetotransport measurements and electron spin resonance spectroscopy consistently show a linear relationship between the two relaxation times over a wide temperature range, clearly manifesting the Elliott–Yafet type of spin relaxation mechanism. The coexistence of an ultra-long spin lifetime of milliseconds and the coherent band-like transport, resulting in a micrometre-scale spin diffusion length, constitutes a key step towards realizing spintronic devices based on organic single crystals.
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Takeya, J. et al. Very high-mobility organic single-crystal transistors with in-crystal conduction channels. Appl. Phys. Lett. 90, 102120 (2007).
Minemawari, H. et al. Inkjet printing of single-crystal films. Nature 475, 364–367 (2011).
Mitsui, C. et al. High-performance solution-processable N-Shaped organic semiconducting materials with stabilized crystal phase. Adv. Mater. 26, 4546–4551 (2014).
Podzorov, V., Menard, E., Rogers, J. A. & Gershenson, M. E. Hall effect in the accumulation layers on the surface of organic semiconductors. Phys. Rev. Lett. 95, 226601 (2005).
Takeya, J. et al. In-crystal and surface charge transport of electric-field-induced carriers in organic single-crystal semiconductors. Phys. Rev. Lett. 98, 196804 (2007).
Uemura, T. et al. Band-like transport in solution-crystallized organic transistors. Curr. Appl. Phys. 12, S87–S91 (2012).
Hava, S. & Auslender, M. Springer Handbook of Electronic and Photonic Materials 441–480 (Springer, 2006).
Dediu, V. A., Hueso, L. E., Bergenti, I. & Taliani, C. Spin routes in organic semiconductors. Nat. Mater. 8, 707–716 (2009).
Watanabe, S. et al. Polaron spin current transport in organic semiconductors. Nat. Phys. 10, 308–313 (2014).
Elliott, R. J. Theory of the effect of spin–orbit coupling on magnetic resonance in some semiconductors. Phys. Rev. 96, 266–279 (1954).
Yafet, Y. in Solid State Physics Vol. 14 (eds Seitz, F. & Turnbull, D.) Ch. 1, 1–98 (Academic, 1963).
Beuneu, F. & Monod, P. The Elliott relation in pure metals. Phys. Rev. B 18, 2422–2425 (1978).
Chazalviel, J. N. Spin relaxation of conduction electrons in n-type indium antimonide at low temperature. Phys. Rev. B 11, 1555–1562 (1975).
Xiong, Z., Wu, D., Vardeny, Z. V. & Shi, J. Giant magnetoresistance in organic spin-valves. Nature 427, 821–824 (2004).
Drew, A. J. et al. Direct measurement of the electronic spin diffusion length in a fully functional organic spin valve by low-energy muon spin rotation. Nat. Mater. 8, 109–114 (2009).
McCamey, D. et al. Hyperfine-field-mediated spin beating in electrostatically bound charge carrier pairs. Phys. Rev. Lett. 104, 017601 (2010).
Nguyen, T., Gautam, B., Ehrenfreund, E. & Vardeny, Z. V. Magnetoconductance response in unipolar and bipolar organic diodes at ultrasmall fields. Phys. Rev. Lett. 105, 166804 (2010).
Soeda, J. et al. Inch-size solution-processed single-crystalline films of high-mobility organic semiconductors. Appl. Phys. Exp. 6, 076503 (2013).
Häusermann, R. et al. Device performance and density of trap states of organic and inorganic field-effect transistors. Org. Electron. 28, 306–313 (2016).
Blülle, B., Troisi, A., Häusermann, R. & Batlogg, B. Charge transport perpendicular to the high mobility plane in organic crystals: bandlike temperature dependence maintained despite hundredfold anisotropy. Phys. Rev. B 93, 035205 (2016).
Troisi, A. Dynamic disorder in molecular semiconductors: charge transport in two dimensions. J. Chem. Phys. 134, 034702 (2011).
Fratini, S., Mayou, D. & Ciuchi, S. The transient localization scenario for charge transport in crystalline organic materials. Adv. Funct. Mater. 26, 2292–2315 (2016).
Malissa, H. et al. Room-temperature coupling between electrical current and nuclear spins in OLEDs. Science 345, 1487–1490 (2014).
Waters, D. et al. The spin-Dicke effect in OLED magnetoresistance. Nat. Phys. 11, 910–914 (2015).
Alger, R. S. Electron Paramagnetic Resonance: Techniques and Applications (John Wiley, 1968).
Marumoto, K., Kuroda, S.-i., Takenobu, T. & Iwasa, Y. Spatial extent of wave functions of gate-induced hole carriers in pentacene field-effect devices as investigated by electron spin resonance. Phys. Rev. Lett. 97, 256603 (2006).
Matsui, H., Hasegawa, T., Tokura, Y., Hiraoka, M. & Yamada, T. Polaron motional narrowing of electron spin resonance in organic field-effect transistors. Phys. Rev. Lett. 100, 126601 (2008).
Wu, M. W., Jiang, J. H. & Weng, M. Q. Spin dynamics in semiconductors. Phys. Rep. 493, 61–236 (2010).
Nguyen, T. D. et al. Isotope effect in spin response of π-conjugated polymer films and devices. Nat. Mater. 9, 345–352 (2010).
Lou, X. et al. Electrical detection of spin transport in lateral ferromagnet–semiconductor devices. Nat. Phys. 3, 197–202 (2007).
Drew, A. J. et al. Intrinsic mobility limit for anisotropic electron transport in Alq3 . Phys. Rev. Lett. 100, 116601 (2008).
Wetzelaer, G., Koster, L. & Blom, P. Validity of the Einstein relation in disordered organic semiconductors. Phys. Rev. Lett. 107, 066605 (2011).
Yu, Z. Spin–orbit coupling and its effects in organic solids. Phys. Rev. B 85, 115201 (2012).
J.Tsurumi was supported by a Grant-in-Aid for JSPS (Japan Society for the Promotion of Science) Research Fellows. S.W. thanks PRESTO-JST ‘Hyper-nano-space design toward Innovative Functionality (Grant No. JPMJPR151E)’, Leading Initiative for Excellent Young Researchers (LEADER-JSPS), and the Noguchi Institute for financial support. T.O. thanks PRESTO-JST ‘Molecular Technology and Creation of New Functions (Grant No. JPMJPR13K5)’. This work was partly supported by a KAKENHI Grant-in-Aid (No. 15H05455) from JSPS. The authors thank H. Ishii of Tsukuba University and S. Fratini of Institut Néel for stimulating discussions. We thank Asahi Glass Co., Ltd. for providing EPRIMA AL.
The authors declare no competing financial interests.
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Tsurumi, J., Matsui, H., Kubo, T. et al. Coexistence of ultra-long spin relaxation time and coherent charge transport in organic single-crystal semiconductors. Nature Phys 13, 994–998 (2017). https://doi.org/10.1038/nphys4217
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