HfTe5 is a member of layered transition metal pentatelluride material family. It crystallizes in orthorhombic phase and our crystals exhibit perfectly layered nature. HfTe5 is at the boundary of weak & strong topological insulator (TI) and might crossover to a Dirac semimetal. It also exhibit superconducting state under applied hydrostatic pressure. Our crystals are grown slowly in 2 months time period using our own growth techniques using 6N purity precursors. Resulting crystals have mm size single domains (world record), perfectly layered nature (ideal for exfoliation and large area monolayer production). The material exfoliates rather easily but in air the surface transforms into TeO2 or other tellurium oxide complexes due to high electron affinity of Hf and HfTe5 surfaces. Bulk crystals are stable in air but monolayer require handling in the glovebox or inert gas conditions. Samples are shipped under microTorr pressure sample boxes back-filled with Ar to safely ship the samples.
Samples can be easily exfoliated into HfTe5 sheets wherein each HfTe5 chain is quasi-weakly bonded to each other.
The properties of HfTe5 vdW crystals
Sample size ~2-4 mm in size Material properties Anisotropic topological insulator, semimetal, superconductor Crystal structure Orthorhombic phase Unit cell parameters a= 0.403 nm b=0.816 nm, c=1.388 nm, α=β=90°, γ=104.3° Production method Chemical vapor transport 99.9995% purity Characterization methods SIMS, XRD, EDS, Raman