LAUSR

Abstract The relation between metal order-disorder and magnetic properties in the solid solution Hf1–xTixMnSb2 (0 ≤ x ≤ 1) with the NiAs structure is investigated. The synchrotron X-ray diffraction studies have revealed that two-dimensional (2D) metal-ordered structure in HfMnSb2 persists up to x = 0.15, though its degree of metal order decreases with x. Although the NiAs-like phase is not formed for 0.2 ≤ x ≤ 0.3, a metal disordered phase appears for x ≥ 0.4. A conical spin order is only found in the metal-ordered region and is fairly robust against partial cation disorder, while the completely metal-disordered region is a ferromagnetic state, providing firm evidence that the presence/absence of metal order essentially defines the ground state. Neutron depolarization measurement for HfMnSb2 suggests possible successive phase transitions.