Fig. 4: Band structure of Bi88Sb12.
From: A magneto-thermoelectric with a high figure of merit in topological insulator Bi88Sb12
a, Band structure of Bi88Sb12 under zero magnetic field. b, An enlarged view of the band structure close to the Fermi level at the T and L points. Inset shows schematic of the composition dependence of the band structures of Bi1–xSbx, with x ranging from 0 to 12%. A band gap Eg of around 17 meV is found in Bi88Sb12. c, Brillouin zone and electron Fermi pockets with a Fermi energy at 20 meV. d, Schematic illustration of the band dispersion with Zeeman splitting. A large g-factor in Bi1–xSbx would split the degenerate Fermi surfaces under zero field at L points into two individual pockets, one that is smaller inside (marked #S) and another one that is larger outside (marked #L). The EF is reduced for the #S band and increased for the #L band compared to that in the degenerate state. Here k is a wave vector. e–g, Calculated Seebeck coefficient under Zeeman splitting: total Seebeck coefficient (e), Seebeck coefficient contributed by #S band (f) and Seebeck coefficient contributed by #L band (g). The total Seebeck coefficient presents a fallback after reaching the maximum at lower temperatures, in good agreement with the experiment.
