Effect of Trigonal Warping on Landau Levels of Graphite

We have devised a successive approximation scheme for taking account of the trigonal warping (γ3) terms in the calculation of the lower‐lying magnetic levels of graphite at fields ⩾ 20 kG. A two‐component effective Hamiltonian has been introduced for these levels. Starting from analytic expressions in the case γ;3 = 0, straightforward and simple iteration schemes have been devised (i) to take account of the higher levels and (ii) to obtain the γ3 contributions. It is found that the trigonal warping changes the levels only by a few per cent except for the n = 0 levels. The levels n = 0, 1, 2, 3 have been calculated for a range of fields from 20 to 200 kG.