Collective magnetic state induced by charge disorder in the non-Kramers rare-earth pyrochlore Tb2ScNbO7

Geometrical frustration, as in pyrochlore lattices made of corner-sharing tetrahedra, precludes the onset of conventional magnetic ordering, enabling the stabilization of fluctuating spin states at low temperature. Disorder is a subtle ingredient that can modify the nature of these exotic nonordered phases. Here, we study the interplay between disorder and magnetic frustration in the new pyrochlore ${\mathrm{Tb}}_{2}{\mathrm{ScNbO}}_{7}$ where the nonmagnetic site presents a charge disorder ${\mathrm{Nb}}^{5+}/{\mathrm{Sc}}^{3+}$. Its quantification with sophisticated diffraction techniques (electrons, x-rays, neutrons) allows us to estimate the distribution of the splitting of the magnetic ${\mathrm{Tb}}^{3+}$ non-Kramers ground-state doublets and to compare it with excitations measured in inelastic neutron scattering. Combining macroscopic and neutron scattering measurements, we show that a spin glass transition occurs at 1 K while retaining strong spin liquid correlations. Our results suggest that ${\mathrm{Tb}}_{2}{\mathrm{ScNbO}}_{7}$ stabilizes one of the novel disorder-induced quantum spin liquid or topological glassy phases recently proposed theoretically.