Individual carbon nanotubes (CNTs) offer high electrical conductivity, tensile strength, and flexibility, but these properties are diminished in randomly oriented structures. Aligned CNT fibers retain good conductivity (up to 10.9 MS/m) but are still inferior to individual CNTs. We have investigated electronic transport phenomena in these fibers through temperature- and magnetic field-dependent measurements, finding that the conductivity decreases with decreasing temperature at low temperatures due to quantum conductance corrections. Using a combination of 3D and 1D weak localization (WL) models, we explained the observed magnetoresistance and discuss their dimensionality in detail.

Low-temperature studies on individual CNT bundles showed significant quantum corrections, with WL and universal conductance fluctuations (UCF) providing consistent phase coherence length estimates (tens of nanometers). However, UCF amplitude and magnetic field asymmetry suggest a coherence length scale similar to the few-micron distance between the voltage probes.

This study enhances the understanding of electronic transport mechanisms in aligned CNT fibers, essential for improving conductivity for various applications.