Fig. 3: The angular dependences of the quantum-oscillations frequency for ZrTe₅.

The θ is the angle between the magnetic field H and the z axis. The experimental data¹² for the frequency F of the oscillations are shown for H lying in the z − x (cycles) and z − y (squares) planes. For dispersion (1), the dashed lines depict dependence (9) with ϵ_zx = 0.096 and ϵ_zy = 0.164. The red solid lines correspond to dispersion (12) and are calculated with Eqs. (13)–(16) and the first set of the parameters from Table 2. Inset: The red lines are the same as in the main panel. To clarify the role of the terms \({\alpha }_{i}{p}_{z}^{2}\) in dispersion (12), the dashed lines are calculated with the same formulas as the red lines, but setting α_c = α_v = 0 in the first set of the parameters [i.e., in fact, with Eq. (9) and ϵ_zx ≈ 0.065, ϵ_zy ≈ 0.11].