Hall Effect in Graphite and Its Relation to the Trigonal Warping of Energy Bands. I. Experimental

Abstract

The Hall effect study of graphite at low magnetic fields below 1.2 kOe has been extended over the four kinds of well-defined specimens and the low temperature range down to 4.2 K. Behaviors of the Hall coefficient are qualitatively accounted for in connection with the structural perfection of specimens by considering the resonance condition of the cyclotron motion of various carriers. The zero-field coefficient of the best-grade specimen exhibits a temperature dependence nearly in agreement with the band-theoretical calculation taking into account the trigonally warped Fermi surfaces in Slonczewski-Weiss-McClure’s model, while those of somewhat less perfect ones are reproduced by ignoring the warping. The contribution of mobile minority holes and the warping effect are concluded to be superimposed with each other.