تقرير
Activated hopping transport in nematic conducting aerogel at low temperatures
| العنوان: | Activated hopping transport in nematic conducting aerogel at low temperatures |
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| المؤلفون: | Tsebro, V. I., Nikolaev, E. G., Lugansky, L. B., Kutuzov, M. S., Khmel'nitskii, R. A., Tonkikh, A. A., Khar'kovskii, A. I. |
| المصدر: | Journal of Experimental and Theoretical Physics (JETP), Vol. 134, No. 2, pp. 222-234 (2022) |
| سنة النشر: | 2022 |
| المجموعة: | Condensed Matter |
| مصطلحات موضوعية: | Condensed Matter - Mesoscale and Nanoscale Physics, Condensed Matter - Materials Science |
| الوصف: | The transport properties of nematic aerogels, which consist of highly oriented Al$_2$O$_3\cdot$SiO$_2$ nanofibers coated with a graphene shell with a large number of defects, are studied. The temperature dependences of the electrical resistivity in the range of 9-40K strictly follow the formula derived to describe the variable range hopping (VRH) conductivity, in which exponent $\alpha$ changes from 0.4 to 0.9 when the number of layers in the graphene shell decreases from 4-6 to 1-2. The dependence of $\alpha$ on the shell thickness can be explained by a simultaneous change in the dimensionality of hopping transport and the character of the energy dependence of the density of localized states near the Fermi level. The fact that $\alpha$ approaches unity at the minimum graphene shell thickness indicates a gradual transition from VRH transport to nearest neighbor hopping (NNH) transport. The magnetoresistance measured at T = 4.2 K is negative, increases significantly with decreasing graphene shell thickness, and is approximated by a formula for the case of weak localization with a good accuracy. The phase coherence lengths are in a reasonable relation with the graphene grain sizes. The conducting aerogels under study complement the well-known set of materials that exhibit hopping electron transport at low temperatures, which is characteristic of media with strong carrier localization, and also a negative magnetoresistance, which usually manifests itself under weak localization conditions. Comment: 15 pages, 11 figures, 4 tables |
| نوع الوثيقة: | Working Paper |
| DOI: | 10.1134/S106377612202008X |
| URL الوصول: | http://arxiv.org/abs/2203.07823 |
| رقم الأكسشن: | edsarx.2203.07823 |
| قاعدة البيانات: | arXiv |
| DOI: | 10.1134/S106377612202008X |
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