Observation of power-law behavior in temperature dependent conductivity of multiwall carbon nanotube/polystyrene composites Ravi Bhatia a, * , I. Sameera b, 1 , V. Prasad c , Reghu Menon c a Department of Physics, Guru Jambheshwar University of Science and Technology, Hisar,125001, India b College of Physical Science and Technology, Sichuan University, Chengdu, 610064, China c Department of Physics, Indian Institute of Science, Bangalore, 560012, India highlights graphical abstract  Temperature dependence of conduc- tivity (300e1.4 K) of MWCNT/PS composites is studied.  Conductivity of MWCNT/PS compos- ites exhibit weak temperature dependence.  Conductivity ratio (s r ) is smaller than 3 for all samples.  Power-law explains the conduction mechanism in the low temperature regime.  Previous similar measurements resulted a pronounced temperature dependence with s r ~500. article info Article history: Available online 23 February 2018 Keywords: Multiwall carbon nanotube Percolative systems Electrical conductivity abstract For last two decades, a pronounced temperature dependence of electrical conductivity (s) in the multiwall carbon nanotube (MWCNT) - based polymer composite (even above the percolation threshold) has been widely reported; the conduction mechanism has been understood by employing conventional models, namely variable range hopping and fluctuation induced tunneling. Herein, we report on the observation of a weak temperature dependence of s in the MWCNT/polystyrene composites above percolation threshold (0.7e7 wt %) at temperatures down to 1.4 K, with a conductivity ratio smaller than 3. The low temperature conductivity data follow power-law exhibiting two slope behavior, with expo- nent values b 1 ~0.10e0.14 (at T > 5 K) and b 2 ~0.23e0.36 (at T < 5 K). The observation of weak temper- ature dependence of s is attributed to high aspect ratio (more than 4000), achievement of high degree of dispersion, and excellent electrical properties of MWCNT as well as optimized composite processing. Further, all the samples exhibit negative magnetoresistance which can be explained within the frame- work of weak localization model. © 2018 Elsevier B.V. All rights reserved. 1. Introduction Low temperature electrical transport properties of both single- and multiwall carbon nanotubes (SWCNT & MWCNT) - based polymer composites have been widely investigated, mostly * Corresponding author. E-mail address: ravibhatia@gjust.org (R. Bhatia). 1 Presently working as DST INSPIRE Faculty at 1Department of Physics, Guru Jambheshwar University of Science and Technology, Hisar-125001, India. Contents lists available at ScienceDirect Materials Chemistry and Physics journal homepage: www.elsevier.com/locate/matchemphys https://doi.org/10.1016/j.matchemphys.2018.02.037 0254-0584/© 2018 Elsevier B.V. All rights reserved. Materials Chemistry and Physics 211 (2018) 258e263