Investigation of the conduction band fermi surface in Bi2Se3 at high electron concentrations

An investigation is made of non‐parabolic terms in the ϵ(k) relation up to the order of [k4] at high electron densities up to 4 × 1019 cm−3. At low electron densities (<1018 cm−3) the Fermi surface is almost an ellipsoid of revolution with its symmetry axis along the trigonal kc axis. Besides, with increasing Fermi energies, a flattening of the Fermi surface in the direction of the kc axis was found, caused by [k4] or higher terms in the ϵ(k) relation. Furthermore the influence of trigonal warping of the Fermi surface was already observed at a concentration of 1.7 × 1018 cm−3 from Shubnikov‐de Haas effect. Here by means of the Shubnikov‐de Haas effect the extremal cross‐sectional areas of the Fermi surface were determined by application of stationary magnetic fields up to 15 T magnetic induction. The parameters of the assumed ϵ(k) model up to [k4] terms were fitted by numerical calculations of the extremal cross‐sectional areas of the Fermi surface perpendicular to arbitrary magnetic field directions and by comparison with the corresponding reciprocal Shubnikov‐de Haas periods.