Magnetic and electrical transport properties of the single-crystalline half-Heusler antiferromagnet DyNiSb

High-quality single crystals of the half-Heusler compound DyNiSb were investigated for their low-temperature thermodynamic and magnetotransport properties. Magnetic susceptibility, heat capacity, and electrical resistivity measurements revealed two distinct magnetic phase transitions at ${T}_{\mathrm{N}1}$ = 7.3 K and ${T}_{\mathrm{N}2}$ = 3.4 K, contrasting with previous reports on polycrystalline samples, which identified only a single transition near ${T}_{\mathrm{N}2}$. Moreover, the studied samples were found to exhibit Metal like conductivity, at odds with a semiconducting behavior reported for the polycrystals. Magnetoresistance measurements performed in both transverse and longitudinal configurations revealed in small magnetic fields a weak antilocalization effect that diminishes with increasing temperature, giving way to a positive, monotonic magnetoresistance at high temperatures. Angular-dependent resistivity studies showed a crossover from fourfold to twofold symmetry with increasing magnetic-field strength, suggesting a field-induced reconstruction of the Fermi surface. Our findings highlight a complex magnetic and electrical transport behavior in DyNiSb, highly sensitive to structural disorder and easily tunable by external magnetic field.