Magnetic field driven dielectric relaxation in non-magnetic composite medium: a low temperature study

TL;DR

This study investigates how magnetic fields influence dielectric relaxation in polyaniline and MWCNT composites at low temperatures, revealing a magnetic field-induced relaxation phenomenon linked to medium inhomogeneity.

Contribution

It demonstrates magnetic field-driven dielectric relaxation in non-magnetic composites and explains it using Parish and Littlewood's magnetocapacitance theory.

Findings

Relaxation observed in MWCNT/PANI composites under magnetic field

Relaxation peak frequency varies with temperature and functionalization

PANI alone shows no relaxation peak under magnetic field

Abstract

The frequency dependence of dielectric constant for composites of polyaniline (PANI) and multi-walled carbon nanotube (MWCNT) with different degree of functionalization is studied at low temperature (down to 4.2 K) and magnetic field (up to 3 Tesla) applied both in parallel and perpendicular direction of ac electric field. A relaxation phenomenon is observed in all the MWCNT/PANI composites by applying magnetic field in both the directions, below 10$^3$ Hz. However, PANI does not show any relaxation peak with applied magnetic field in either direction. The relaxation peak frequency does not depend on the strength of magnetic field but it varies with temperature and degree of functionalization of MWCNT in composites. This relaxation phenomenon occurs due to the inhomogeneity of the medium of two highly mismatched conductive materials at low temperatures. We have tried to explain our results in the light of Parish and Littlewood theory about magnetocapacitance in nonmagnetic composite.