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Weyl fermions are massless chiral fermions that were suggested in quantum field theory more than eight decades ago. Though having not been observed in high-energy physics, Weyl fermions are expected to exist in low-energy excitations of condensed matter systems. TaAs family and HgCr₂Se₄ are two kind of Weyl semimetals that play as the model systems for broken spatial inversion symmetry and broken time-reversal symmetry, respectively. TaAs has been identified as an ideal Weyl semimetal by a series of experiments, while HgCr₂Se₄ is still to be confirmed. For both cases, large-size high-quality crystals are required for ongoing research and future applications. In this work^[1], we address these issues by reporting the chemical vapor transport method for obtaining TaAs single crystals with size of ~10 mm and HgCr₂Se₄ crystals ~5 mm. The crystals have regular morphology and shiny facets, and show good quality in structural, electrical and magnetic characterizations. Growth thermodynamics and crystal morphology are also investigated.

[1] Z. L. Li, H. X. Chen, S. F. Jin et.al., Cryst. Growth Des.16, 3 (2016).