Disruption of the Accidental Dirac Semimetal State in ${\mathrm{ZrTe}}_5$ under Hydrostatic Pressure

We study the effect of hydrostatic pressure on the magnetotransport properties of zirconium pentatelluride. The magnitude of resistivity anomaly gets enhanced with increasing pressure, but the transition temperature $T^{*}$ is insensitive to it up to 2.5 GPa. In the case of $H\parallel b$, the quasilinear magnetoresistance decreases drastically from 3300% (9 T) at ambient pressure to 230% (9 T) at 2.5 GPa. Besides, the change of the quantum oscillation phase from topological nontrivial to trivial is revealed around 2 GPa. Both demonstrate that the pressure breaks the accidental Dirac node in ${\mathrm{ZrTe}}_5$. For $H\parallel c$, in contrast, subtle changes can be seen in the magnetoresistance and quantum oscillations. In the presence of pressure, ${\mathrm{ZrTe}}_5$ evolves from a highly anisotropic to a nearly isotropic electronic system, which accompanies the disruption of the accidental Dirac semimetal state. It supports the assumption that ${\mathrm{ZrTe}}_5$ is a semi-3D Dirac system with linear dispersion along two directions and a quadratic one along the third.

Figure 1

Temperature dependence of the electrical resistivity $\rho (T)$ for ${\mathrm{ZrTe}}_5$ in zero magnetic field under selected pressures. Data are normalized to the value of resistivity at 300 K. The inset shows the evolution of resistivity anomaly $T^{*}$ under pressure.

Figure 2

(a) The magnetoresistance of ${\mathrm{ZrTe}}_5$ at various pressures with $H\parallel b$ and $\mathbf{I}\parallel a$, measured at 0.3 K. Inset schematically displays the arrangements of the magnetic field and current applied for sample No. 1. (b) Shubnikov–de Haas oscillations component $\mathrm{\Delta }{\mathrm{R}}_{H\parallel c}$ as a function of inverse magnetic field taken at different pressures. Data are normalized and shifted for clarity. (c) Pressure dependence of the quantum oscillation frequency (Fermi surface size) and the effective mass. Inset: pressure dependence of the Landau $g$ factor. (d) Landau level index plots of the oscillations at various pressure. Inset summarized the phase factor of SdH oscillation as a function of pressure. The circle (red) and diamond (blue) represent sample No. 1 and sample No. 3, respectively.

Figure 3

(a) The magnetoresistance of ${\mathrm{ZrTe}}_5$ at various pressures with $H\parallel \mathrm{c}$ and $\mathbf{I}\parallel \mathrm{a}$, measured at 0.3 K. Inset schematically displays the arrangements of magnetic field and current applied for sample No. 2. (b) Shubnikov–de Haas oscillations component $\mathrm{\Delta }{\mathrm{R}}_{H\parallel c}$ as a function of inverse magnetic field taken at different pressures. Data are shifted for clarity and arrows indicate the Landau levels. (c) Pressure dependence of the quantum oscillation frequency (Fermi surface size) and the effective mass. (d) Evolution of the anisotropic parameters under pressure.

Figure 4

Schematic illustrations of the band structure evolution under pressure. The light green and pink regions represent the phases of WTI and STI, respectively.