Metallic doped polymers (polyaniline and polypyrrole) have an electromagnetic response [1,2] that,
when analyzed within the standard theory of metals, is provided by an extremely small fraction
of the total number of available electrons ~ 0.1 % (in contrast to ~ 100 % for common metals
such as Cu, Ag, Al, or Ni) but with anomalous long scattering time > 10-13 s (~ 100 times longer
than for common metals). We show that a network of metallic grains (the polymer's crystalline
domains) connected by resonance quantum tunneling through strongly localized states in
surrounding disordered medium produces this behavior. The small fraction of electrons is
assigned to the low density of resonance states and the long scattering time is related to the
narrow width of energy levels in resonance.
Supported in part by ONR
References:
1. R. S. Kohlman et al., Phys. Rev. Lett. 78, 3915 (1997).
2. H. C. F. Martens et al., Phys. Rev. B 63, 07203 (2001).