Low-temperature hysteresis in transport properties of UNi0.5Sb2

• Synthesis of a new batch 2 of the UNi0.5Sb2 single crystals.
• Very precise measurements of ρ(T) and S(T) between 0.3 and 300 K.
• Precise determination of hysteretic features at Tt (T < TN) at zero and 9 T.
• A difference exists between the obtained results and those reported previously.
• Suggestion about the high-T magnetic structure based on the USb2 case.

We report detailed data of the electrical resistivity and thermoelectric power (TEP) measurements carried out at temperatures 0.4–300 K on single crystals of a deficit diantimonide UNi0.5Sb2. Although the composition of this compound and the transition temperature to the antiferromagnetic state are almost the same as those previously reported, we found the hysteretic transition occurring in the ordered state at different temperature (Tt = 81 K) from those estimated in earlier works, i.e. at either Tt = 64 K or Tt1 = 40 K and Tt2 = 85 K. This fact observed in both kinds of applied measurements indicates clearly a high sensitivity of these temperatures [connected to some moment reorientation and the following reconstruction of the Fermi surface (FS)] in this compound, to the used technology of growing its single crystals by different groups of authors. Following the results of a similar character of the parent compound USb2 and taking into account the recent literature reports, we suppose that the observed anomalies in the resistivity and TEP of UNi0.5Sb2 are also caused by the complex electronic structure. Thus changes at its FS in the ordered state (e.g. f -electron dualism leading to band renormalization involving magnons) are forcing the reorientation of the uranium magnetic moments in the successive magnetic unit cells.