Absence of moment fragmentation in the mixed B site pyrochlore oxide Nd₂GaSbO₇

Nd-based pyrochlore compounds (Nd₂B₂O₇) are of particular interest in the framework of moment fragmentation physics. Introduction of charge disorder on a non-magnetic B site in these systems is expected to reduce the symmetry about the Nd site, significantly suppressing moment fragmentation. Here we report on a polycrystalline sample of a Nd pyrochlore with a charge-disordered B-site, Nd₂GaSbO₇. We show that this compound orders into the “all-in, all-out” magnetic structure below T_N = 1 K, one of the highest ordering temperatures reported for a Nd pyrochlore. The Ising-like character of the moments and the dipolar-octupolar nature of the ground state doublet are confirmed via bulk property measurements and crystal field analysis, respectively, both of which are necessary for moment fragmentation. Although inelastic neutron scattering results show a flat mode at 0.253(6) meV, the diffuse neutron scattering was not able to resolve any spin-ice correlations. These results may suggest the absence of moment fragmentation in this system.