ABSTRACT
Many different mechanisms have been predicted for the magnetoresistance in the strong-localization regime. These mechanisms depend on the magnitude of the localization length and of the carrier-carrier interaction. Experimental mag netoresistance measurements were reported for the more concentrated Q .9F and C3.0F fibers, whose temperature-dependent resistivity p(7) exhibits variable-hop ping behavior, characteristic of the strong-localization regime [6]. Both longi tudinal and transverse magnetoresistance curves are shown in Fig. 28 for a C3 0F fiber at the two temperatures 1.2 K and 4.2 K. Figure 28 shows that the trans verse magnetoresistance exhibits a negative magnetoresistance for weak fields, with a qualitative behavior very similar to that measured in weakly localized fibers and attributed to weak-localization effects. This is not surprising since all measurable parameters point to the fact that the Q> 9F fibers lie very close to the metal-insulator transition, and thus the localization length £ and the inelastic scattering length Lt have similar magnitudes [42,48].
