Artículos de revistas
The ferromagnetic behaviour of conducting polymers revisited
Fecha
2008-01-23Registro en:
Journal of Physics-condensed Matter. Bristol: Iop Publishing Ltd, v. 20, n. 3, p. 8, 2008.
0953-8984
10.1088/0953-8984/20/03/035214
WOS:000252922900024
Autor
Universidade de São Paulo (USP)
Universidade Federal de São Carlos (UFSCar)
Universidade Estadual Paulista (Unesp)
Institución
Resumen
The magnetic properties of doped pellets of poly(3-methylthiophene) showing room temperature ferromagnetic behaviour have been discussed in a previous article. The magnetic behaviour was attributed to a weak ferromagnetic phase, due to the superexchange interaction of polarons via the dopant anions. The Dzialoshinsky-Morya interaction among canted spins was proposed to explain the ferromagnetism. In this article the main conclusions of that work concerning the magnetic behaviour are revised. The basic assumption now is that the magnetic moments are spin 1/2 polarons that can interact antiferromagnetically and/or ferromagnetically. In the small crystalline regions of the polymer, which are identified with the polymer portion that remains ferromagnetic at room temperature, the interaction gives rise to S = 0 and 1 bipolarons and the S = 1 triplet state is lower in energy. In the disordered region, disorder will prevent the complete S = 1 and 0 coupling and bands of polarons ferromagnetically and antiferromagnetically coupled will appear. Using this approach, all the magnetization data can be qualitatively explained, as well as the electron spin resonance data.