Fig. 2: Probing the electronic spectrum of ZrTe₅ in magnetic fields.

a Magnetization M as a function of temperature T with a 2 T magnetic field B applied along the b-axis of Sample C. b M as a function of T with a 50 mT applied along the b-axis of Sample C. c M as a function of T with a 100 mT applied along the a-axis (black line) and c-axis (dark yellow line) of Sample C. d De Haas-van Alphen oscillations observed in M as a function of B applied along the b-axis at various T on Sample C. The inset shows a zoom-out of M as a function of B applied along the b-axis at 2 K. e Differential conductance dI/dV as a function of bias voltage (energy E) with respect to the Fermi level E_F (dotted line) for various B applied along the b-axis of Sample D at 0.4 K. The conduction band edges are marked with CB₁ and CB₂, the valence band edge is marked with VB₁. f Sound-velocity variation Δv_s/v_s of the longitudinal sound mode (propagation along the a-axis) as a function of the magnetic field applied along the b-axis at 2 K on Sample E. The black line is experimental data, the green line a theoretical model (see “Methods”), based on a Dirac Hamiltonian. g Sound attenuation Δα of the longitudinal mode (propagation along the a-axis, polarization vector along the a-axis) as a function of the magnetic field applied along the b-axis at 2 K on Sample E. None of the experiments shows signatures of a charge-density–wave formation.