Three-dimensional topological semimetal phase in layered $\mathrm{TaNi}{\mathrm{Te}}_5$ probed by quantum oscillations

Recently layered compound $\mathrm{TaNi}{\mathrm{Te}}_5$ was proposed to be two-dimensional (2D) topological semimetals. Here we report the detailed investigation on $\mathrm{TaNi}{\mathrm{Te}}_5$ single crystals through magnetotransport and de Hass−van Alphen (dHvA) effect studies. Strong quantum oscillations with multiple periodicities have been observed. By analyzing the quantum oscillations, we provide evidence of nontrivial Berry phase with a 3D Fermi surface character in layered $\mathrm{TaNi}{\mathrm{Te}}_5$. Our work suggested that layered $\mathrm{TaNi}{\mathrm{Te}}_5$ should be 3D topological semimetal which offers a platform to explore exotic properties in low-dimensional topological semimetals.

Figure 1

(a) Crystal structure of $\mathrm{TaNi}{\mathrm{Te}}_5$ (space group $Cmcm$). (b) XRD pattern of the as-grown single crystals. Inset: Typical optical image of the grown $\mathrm{TaNi}{\mathrm{Te}}_5$ single crystals. (c) Temperature-dependent resistivity ρ measured with the current applied along the $c$ axis. (Inset) The MR as function of magnetic field measured at $T=2\mathrm{K}$. (d) The magnetic field-dependent magnetization as function of $B$ at $T=2\mathrm{K}$ with $B\parallel b$ axis. (Lower inset) Temperature-dependent magnetic susceptibility. (Upper inset) The enlargement of the field-dependent magnetization at $T=2\mathrm{K}$.

Figure 2

(a) The MR as function of magnetic field at various temperatures with $B\parallel b$ axis. (b) FFT spectra of SdH oscillations at different temperatures. Inset: the oscillatory component ΔR as function of 1/B at 2 K extracted from high magnetic field MR.

Figure 3

(a) Magnetic field dependence of magnetic torque $\tau$ at various temperatures with $B$ along the $b$ axis. (b) The oscillation component Δτ as function of $1/B$ at various temperatures after subtracting the smooth background. (Inset) The fit of the oscillation pattern at $T=2\mathrm{K}$ to the multiband LK formula. (c) (Left) FFT spectra of dHvA oscillations at different temperatures. (Right) The enlarged FFT spectra from 800 to 1200 T. (d) The temperature dependence of the FFT amplitudes for band $\alpha$ and $\beta$. The effective masses were extracted from the fitted curve (red line) using LK formula. (Inset) The Dingle plots of dHvA oscillations at 2 K. (e) LL index $n$ vs 1/$B$ at 2 K with the B//$b$ axis. (Inset) Nonzero intercepts with the $n$ axis obtained by the best linear fit.

Figure 4

(a) The magnetic field-dependent magnetic torque $\tau$ under various angles at $T=2\mathrm{K}$. The curves have been shifted for clarify. (Inset) Schematic of the measurement configuration with $\theta$ the angle between the applied field and the $b$ axis. (b) The oscillatory components after subtracting the smooth background as a function of $1/B$ at various angles. (c) (Left) The FFT spectra for different angles indicated. (Right) Enlarged FFT spectra in the range of $800\sim 1200\mathrm{T}$. (d) The angular dependences of the oscillation frequencies of α (pink), β (blue), γ (olive), and η (violet) pockets with the fits of 2D FS (dashed lines) and 3D ellipsoid FS (solid lines).