title: Evidence of weak ferromagnetism in doped plasticized polyaniline (PANI-DDoESSA)0.5 from electron spin resonance measurements.
abstract: X-band electron spin resonance (ESR) measurements have been performed on a conducting free-standing film of polyaniline plasticized and protonated with di-n-dodecyl ester of sulfosuccinic acid (DDoESSA). The magnetic field was applied parallel and perpendicular to the plane of the film. At around 75 K a transition is observed from Pauli susceptibility to a localized state in which the spin 1/2 polarons behave as spin 1/2 dimers. A rough estimation of the intradimer and interdimer exchange constants is obtained. Below 5 K, ESR data reveal a weak ferromagnetism with the Dzyaloshinskii-Moriya vector mainly oriented in the plane of the film. The existence of a relatively well-defined n-fold axis along the chain direction in the crystalline regions confers a symmetry compatible with such analysis.
authors: Departamento de Física, Instituto de Geociências e Ciências Exatas, Universidade Estadual Paulista (UNESP), Rio Claro, SP, Brazil.
authors: V T
authors: VT
authors: Santana
authors: O R
authors: OR
authors: Nascimento
authors: D
authors: D
authors: Djurado
authors: J P
authors: JP
authors: Travers
authors: A
authors: A
authors: Pron
authors: L
authors: L
authors: Walmsley