A Simple Two-Band Theory of Galvanomagnetic Effects in Graphite in Relation to the Magnetic Field Azimuth

Abstract

A simple two-band theory of galvanomagnetic effects in graphite has been developed so as to involve not only the magnetic field intensity (H) but its azimuth (θ) with respect to the c-axis, which successfully accounts for the complicated behavior of transverse magnetoresistance (Δρ/ρ0) in an iron-melt graphite previously found by the authors. The theory verifies the relation ν≃ξ when Δρ/ρ0 is expressed in the conventional form Δρ/ρ0∝Hν cosξ θ, and predicts that the more perfect the compensation and/or the lower the mobility of carriers becomes, the closer the magnetoresistance conforms to the H2-law, while a considerable deviation is observed in the intermediate ranges. Discussions are also given on the contributions of minority carriers.