Magnetic ordering in the Ising antiferromagnetic pyrochlore NdScNbO.

The question of structural disorder and its effects on magnetism is relevant to a number of spin liquid candidate materials. Although commonly thought of as a route to spin glass behaviour, here we describe a system in which the structural disorder results in long-range antiferromagnetic order due to local symmetry breaking. NdScNbOis shown to have a dispersionless gapped excitation observed in other neodymium pyrochlores below= 0.37 K through polarized and inelastic neutron scattering. However the dispersing spin waves are not observed. This excited mode is shown to occur in only 14(2)% of the neodymium ions through spectroscopy and is consistent with total scattering measurements as well as the magnitude of the dynamic moment 0.26(2). The remaining magnetic species order completely into the all-in all-out Ising antiferromagnetic structure. This can be seen as a result of local symmetry breaking due disordered Scand Nbions about the-site. From this work, it has been established that-site disorder restores the dipole-like behaviour of the Ndions compared to the NdBOparent series.