Microstructure and Negative Magnetoresistance in Pitch-derived Carbon-fibers

Nysten, Bernard [UCL] Issi, Jean-Paul [UCL] Barton, R. [Du Pont, Wilmington, DE] Boyington, D. R. [Du Pont, Wilmington, DE] Lavin, Jerry G. [Du Pont, Wilmington, DE]

The transverse magnetoresistance of various pitch-derived carbon fibres has been measured at 4.2 and 77 K as a function of magnetic field up to 1.2 T. The magnetoresistance was found to be negative for all the fibres studied. The data have been interpreted using the two-dimensional (2D) weak localization theory and have been related to the structural parameters determined by x-ray diffraction. The results are also compared with those obtained on other pitch-based fibres and on pregraphitic carbons. They show that the negative magnetoresistance is related to the microstructure of the material and thus could be used as a tool to characterize the defect structure of carbon fibres.