Magnetic Phase Diagram of the UP1−<i>x</i>S<i>x</i> System

Abstract

The magnetic phase diagram of the UP1−xSx system (0≤x≤1) was investigated in a temperature range from 5° to 300°K by neutron diffraction with powder samples. The types of ordering, ordered moments, and the temperature dependence were determined. The crystal structure of the solid solutions is fcc (NaCl-type). As x increases three types of magnetic ordering are observed: Antiferromagnetic (AF) type-I, AF type-IA, and ferromagnetic. The type-IA ordering consists of ferromagnetic sheets as in type-I, but whereas in the latter the sheets are arranged +−+−..., they are now stacked ++−−.... For x=0 (UP) and 0.02 the order is AF-I. For 0.05≤x≤0.10, the AF-I structure is present at high temperatures but a transition to AF-IA occurs at low temperatures. The temperature of this transition increases with x. For x=0.15 and 0.20 the magnetic structure is AF-IA. The samples with x=0.25 and 0.28 are initially ferromagnetic, but at low temperatures a transition to the AF-IA structure occurs. An intermediate structure probably involving a complicated spin arrangement is also present for x=0.25 before the AF-IA structure is established. For x≥0.33 the ordering is ferromagnetic.