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$∗\approx$34 K. Powder and single-crystal neutron diffraction establish an ordered magnetic moment of (3.9$\pm$0.1)$\mu$B/f.u., consistent with the effective moment inferred from the Curie-Weiss dependence of the susceptibility. Below TN, the Mn sublattice displays commensurate type-II antiferromagnetic order with propagation vectors and magnetic moments along \langle{}111̊angle{} (magnetic space group R[I]3c). Surprisingly, below T$∗$, the moments tilt away from \langle{}111̊angle{} by a finite angle $\delta\approx$11$i̧rc$, 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 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$∗\approx$34 K. Powder and single-crystal neutron diffraction establish an ordered magnetic moment of (3.9$\pm$0.1)$\mu$B/f.u., consistent with the effective moment i...     »