Eur. Phys. J. B 83, 57-61 (2011)
https://doi.org/10.1140/epjb/e2011-20388-2

Interplay of Curie-type and Pauli-type magnetic susceptibilities in HCl-doped polyaniline pellets

¹ Department of Physics, Faculty of Science, University of Zagreb, Bijenička cesta 32, 10000 Zagreb, Croatia
² Institute for Medical Research and Occupational Health, Ksaverska cesta 2, 10000 Zagreb, Croatia

Corresponding author: ^a mnovak@phy.hr

Received: 23 May 2011
Published online: 15 September 2011

Abstract

The static magnetic susceptibility (χ) of own-made HCl-doped polyaniline pellets is investigated experimentally over the full range of the protonation level Y and in the temperature (T) range 10–300 K. The obtained results suggest that χ and the electrical conductivity σ – which is known from previous work – are interrelated. Namely, there is a weakly Y dependent crossover temperature T^* where both χ and σ undergo notable changes. In χ, this refers to a simultaneous enhancement (reduction) of the Pauli-type susceptibility χ_P and reduction (enhancement) of the Curie constant C at T = T^* when T increases (decreases). Below T < T^*, where thermal effects are weak to moderate, a steep increase of χ_P(Y) around Y = 0.3 occurs together with a drop of C(Y). The above findings are consistent with a picture in which, at T^*, spins that disappear from C reappear in χ_P, and vice versa. This model is used to address the longitudinal and transversal electron localisation lengths as functions of Y, the former being estimated to take values in the range 7–8 Åand the latter in the range 1–2 Å.