Optimized growth of large-size, high quality $\text{ZrTe}_5$ single crystals enabling clear quantum oscillations in electrical transport

Abstract

Quantum oscillation with nontrivial Berry phase is one of the characteristics of topological materials. As a Dirac semimetal candidate, zirconium pentatelluride ($\text{ZrTe}_5$) stands out as an intriguing material for investigating topological phase transitions and Dirac fermion physics; however, the extreme sensitivity of its electronic properties to stoichiometric variations and crystalline defects has hindered consistent experimental observation. Here, we report an optimized Te-flux synthesis method designed to produce centimeter-scale, high-quality single crystals meanwhile minimizing extrinsic carrier contamination. Comprehensive morphology, structural and chemical characterization, including scanning electron microscopy, Laue backscattering and Rietveld refinement, confirms a high-purity $Cmcm$ phase with excellent crystallinity. Furthermore, magnetotransport measurements reveal a remarkably low Shubnikov-de Haas oscillation onset field ($B \approx 0.38$ T) and access to the the quantum limit at $B \approx 1.3$ T, indicative of low carrier density and high carrier mobility. These results demonstrate that growth control is crucial for stabilizing intrinsic electronic behavior in $\text{ZrTe}_5$, establishing a robust platform for exploring topological phase transitions and exotic quantum phenomena in topological semimetals.

Figures (4)

• Figure 1: (a) Purified Te by annealing at $700^\circ\text{C}$ with carbon. (b) Schematic illustration of the growth ampoule assembly, featuring a quartz tube with one catch crucible and a necking design to support a specialized alumina filter. (c) Temperature profile of the optimized Te-flux growth process. (d) Photograph of the quartz tube after centrifugation at $490^\circ\text{C}$, showing the separation of the residual Te-flux from the harvested $\text{ZrTe}_5$ crystals.
• Figure 2: (a– b) Optical images of typical $\text{ZrTe}_5$ single crystals grown by previously reported method and the optimized Te-flux method, with (b) showing large-size, ribbon-like morphologies with lengths exceeding 1 cm. (c) Scanning electron microscopy (SEM) image of a representative crystal, displaying a flat, high-quality surface. (d) High-magnification SEM image of the area highlighted in (c), revealing the distinct layered structure characteristic of $\text{ZrTe}_5$.
• Figure 3: (a– b) Schematic illustration of the orthorhombic crystal structure of $\text{ZrTe}_5$ viewed along the $a$- and $b$-axes, highlighting the 1D $\text{ZrTe}_3$ chains and the layered 2D structure. (c) Laue backscattering pattern of a flux-grown single crystal, showing sharp, well-defined spots that match the calculated pattern (bottom). (d) Powder X-ray diffraction (XRD) pattern and Rietveld refinement of crushed $\text{ZrTe}_5$ crystals. (e) XRD pattern of a $\text{ZrTe}_5$ single crystal showing $(0k0)$ reflections. Insets show a rocking curve of the $(020)$ peak with a FWHM of $0.06^\circ$. (f) EDS elemental mapping for Zr (green) and Te (blue), showing a uniform distribution of elements across the crystal. (g) EDS spectrum confirming the chemical composition, with an atomic ratio of approximately 1:4.95, indicating near-ideal stoichiometry.
• Figure 4: (a) Temperature dependence of the longitudinal resistivity $\rho_{xx}$, showing the characteristic resistivity anomaly peak at $T_p \approx 90$ K. (b) Low-temperature $\rho_{xx}$ versus magnetic field $\mu_0 H$, exhibiting clear Shubnikov-de Haas (SdH) oscillations at remarkably low onset fields ($B \approx 0.38$ T), confirming high mobility. (c) Hall resistivity $\rho_{xy}$ at $T = 1.9$ K. The dashed line represents a linear fit for $|B| < 0.6$ T, from which an ultra-low carrier density ($n = 9.20 \times 10^{16}$ cm$^{-3}$) and ultra-high mobility ($\mu = 5.58 \times 10^5$ cm$^2$ V$^{-1}$ s$^{-1}$) are extracted. (d) Angle-dependent $\rho_{xy}$ curves as the magnetic field is rotated from the $b$-axis to the $ac$ plane.