We report single crystal growth of the series of CeT Al 3 compounds with T = Cu, Ag, Au, Pd and Pt by means of optical float zoning. High crystalline quality was confirmed in a thorough characterization process. With the exception of CeAgAl 3 , all compounds crystallize in the non-centrosymmetric tetragonal BaNiSn 3 structure (space group: I4mm, No. 107), whereas CeAgAl 3 adopts the related orthorhombic PbSbO 2 Cl structure (Cmcm, No. 63). An attempt to grow CeNiAl 3 resulted in the composition CeNi 2 Al 5 . Low temperature resistivity measurements down to ∼0.1 K did not reveal evidence suggestive of magnetic order in CePtAl 3 and CePdAl 3 . In contrast, CeAuAl 3 , CeCuAl 3 and CeAgAl 3 display signatures of magnetic transitions at 1.3 K, 2.1 K and 3.2 K, respectively. This is consistent with previous reports of antiferromagnetic order in CeAuAl 3 , and CeCuAl 3 as well as ferromagnetism in CeAgAl 3 , respectively.

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We report the low-temperature properties of phase-pure single crystals of the half-Heusler compound CuMnSb grown by means of optical float-zoning. The magnetization, specific heat, electrical resistivity, and Hall effect of our single crystals exhibit an antiferromagnetic transition at TN = 55 K and a second anomaly at a temperature T * ≈ 34 K. Powder and single-crystal neutron diffraction establish an ordered magnetic moment of (3.9 ± 0.1) µB/f.u., consistent with the effective moment inferred from the Curie-Weiss dependence of the susceptibility. Below TN, the Mn sublattice displays commensurate type-II antiferromagnetic order with propagation vectors and magnetic moments along 111 (magnetic space group R[I]3c). Surprisingly, below T * , the moments tilt away from 111 by a finite angle δ ≈ 11 • , forming a canted antiferromagnetic structure without uniform magnetization consistent with magnetic space group C[B]c. Our results establish that type-II antiferromagnetism is not the zero-temperature magnetic ground state of CuMnSb as may be expected of the face-centered cubic Mn sublattice.

We report the design of a radio-frequency induction-heated rod casting furnace that permits the preparation of polycrystalline ingots of intermetallic compounds under ultra-high vacuum compatible conditions. The central part of the system is a bespoke water-cooled Hukin crucible supporting a casting mold. Depending on the choice of mold, typical rods have a diameter between 6 mm and 10 mm and a length up to 90 mm, suitable for single-crystal growth by means of float-zoning. The setup is all-metal sealed and may be baked out. We find that the resulting ultra-high vacuum represents an important precondition for processing compounds with high vapor pressures under a high-purity argon atmosphere up to 3 bar. Using the rod casting furnace, we succeeded to prepare large high-quality single crystals of two half-Heusler compounds, namely the itinerant antiferromagnet CuMnSb and the half-metallic ferromagnet NiMnSb.

We report the angular dependence of three distinct de Haas-van Alphen (dHvA) frequencies of the torque magnetization in the itinerant antiferromagnet CrB2 at temperatures down to 0.3 K and magnetic fields up to 14 T. Comparison with the Fermi surface calculations considering an incommensurate cycloidal magnetic order suggests that two of the observed dHvA oscillations arise from electron-like Fermi surface sheets formed by bands with strong B-px,y character. The third orbit could correspond to a Cr-d derived Fermi surface sheet. The measured effective masses of these Fermi surface sheets display strong enhancements of a factor of about two over the calculated band masses which can be attributed to electron-phonon coupling and electronic correlations. Signatures of further heavy d-electron bands that are predicted by the calculations are not observed in the temperature and field range studied. In view that the B-p bands are at the heart of conventional high-temperature superconductivity in the isostructural MgB2, we consider possible implications of our findings for nonmagnetic CrB2 and an interplay of itinerant antiferromagnetism with superconductivity.