Santana, V. T. [UNESP]Nascimento, O. R.Djurado, D.Travers, J. P.Pron, A.Walmsley, L. [UNESP]2014-05-272014-05-272013-03-20Journal of Physics Condensed Matter, v. 25, n. 11, 2013.0953-89841361-648Xhttp://hdl.handle.net/11449/74854X-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. © 2013 IOP Publishing Ltd.engA transitionsChain directionCrystalline regionsDzyaloshinskii-moriyaElectron spin resonance measurementsExchange constantsFreestanding filmsLocalized stateProtonatedRough estimationSpin 1/2Weak ferromagnetismX-band electron spin resonancesPolyanilineFerromagnetismArtigo10.1088/0953-8984/25/11/116004WOS:000315597600022Acesso restrito2-s2.0-84874274684