We present details of materials synthesis, crystal structure, and anisotropic magnetic properties of single crystals of CeAlGe, a proposed type-II Weyl semimetal. Single-crystal x-ray diffraction confirms that CeAlGe forms in a noncentrosymmetric I41md space group, in line with predictions of nontrivial topology. Magnetization, specific heat, and electrical transport measurements were used to confirm antiferromagnetic order below 5 K, with an estimated magnon excitation gap of Δ = 9.11 K from heat capacity and hole-like carrier density of 1.4 x 1020 cm-3 from Hall effect measurements. The easy magnetic axis is along the  crystallographic direction, indicating that the moment lies in the tetragonal ab plane below 7 K. A spin-flop transition to less than 1 μB/Ce is observed to occur below 30 kOe at 1.8 K in the M(H) (H||a) data. Small magnetic fields of 3 and 30 kOe are sufficient to suppress magnetic order when applied along the a and c axes, respectively, resulting in a complex T-H phase diagram for H||a and a simpler one for H||c.
H. Hodovanets et al., "Single-Crystal Investigation of the Proposed Type-II Weyl Semimetal CeAlGe," Physical Review B, vol. 98, no. 24, article no. 245132, American Physical Society (APS), Dec 2018.
The definitive version is available at https://doi.org/10.1103/PhysRevB.98.245132
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20 Dec 2018
U.S. Department of Energy, Grant GBMF4419