Hydrostatic pressure study of single-crystalline U Ni 0.5 Sb 2

We studied single crystals of the antiferromagnetic compound U Ni 0.5 Sb 2 ( T N ≈ 161 K ) by means of measurements of magnetic susceptibility ( χ ) , specific heat ( C p ) , and electrical resistivity ( ρ ) at ambient pressure, and resistivity under hydrostatic pressures up to 20 kbars , in the temperature range from 1.9 to 300 K . The thermal coefficient of the electrical resistivity ( d ρ ∕ d T ) changes drastically from positive below T N to negative above, reflecting the loss of spin-disorder scattering in the ordered phase. Two small features in the ρ versus T data centered near 40 and 85 K correlate well in temperature with features in the magnetic susceptibility and are consistent with other data in the literature. These features are quite hysteretic in temperature, i.e., the difference between the warming and cooling cycles are about 10 and 6 K , respectively. The effect of pressure is to raise T N at the approximate rate of 0.76 K ∕ kbar , while progressively suppressing the amplitude of the small features in ρ versus T at lower temperatures and increasing the thermal hysteresis.