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We investigate how local magnetic correlations evolve when the classical pyrochlore spin ice Ho₂Ti₂O₇ is transformed into the partially disordered stuffed compound Ho₂TiO₅. Neutron scattering measurements were analyzed using real space magnetic pair distribution function, reciprocal space reverse Monte Carlo, and half-polarized neutron powder diffraction methods to connect the average crystal structure with local magnetic correlations. Both compounds retain long-range 𝐹𝑑3𝑚 symmetry, but in Ho₂TiO₅ the average structure does not fully capture the local Ho–O, Ti–O, and O–O bond-length disorder associated with partial Ho/Ti occupancy. Despite this disorder, half-polarized neutron powder diffraction shows that the Ho moments retain local ⟨111⟩ Ising anisotropy and form spin-in/spin-out configurations on the tetrahedral network. In Ho₂Ti₂O₇, real- and reciprocal-space analyses show a nearly ideal 2-in/2-out spin ice state at 0.3 K, with ∼95% of tetrahedra satisfying the ice rule, followed by progressive thermal disordering on warming. In Ho₂TiO₅, most tetrahedra are magnetically incomplete because some tetrahedral vertices are occupied by nonmagnetic Ti rather than Ho; nevertheless, the dominant incomplete configurations are 2-in/1-out and 1-in/2-out, which are locally compatible with the ice rule if the missing Ho spin is restored. Ho₂TiO₅ is therefore a vacancy-disrupted spin ice in which the local ⟨111⟩ Ising character and short-range spin-in/spin-out correlations persist on a topologically incomplete magnetic network, while collective ice-rule correlations are strongly disrupted.

Magnetostructural coupling plays a crucial role in numerous types of quantum materials and functional magnetic materials. Here, we investigate the magnetostructurally active ferromagnet MnSb, whose derivative compounds Mn_1+xSb are strong candidates for magnetocaloric applications. We reveal an unusually large spontaneous magnetostriction effect in MnSb, resulting in a relative unit cell expansion of up to 1% and an extended temperature region of negative thermal expansion of the crystallographic axis. This magnetovolume effect is exceptional not only because of its magnitude, but also because the volume increase begins in the paramagnetic phase and exhibits unconventional linear scaling with the short-range ferromagnetic correlations as the temperature is lowered, before switching to quadratic scaling with the long-range-ordered magnetic moment below the transition. We explain this exceptional behavior through unusual trilinear couplings among the lattice strain and domains of distinct magnetic order parameters. Heat capacity measurements also provide new thermodynamic information about MnSb, including determination of the Debye and Einstein temperatures to be 164 and 296 K, respectively. These findings greatly expand our understanding of MnSb and provide insights into the fundamental materials physics of magnetostructural coupling in the presence of short-range magnetic correlations, with potential for broad applicability.

Kitaev iridates are an important class of spin-orbit-entangled quantum materials, where bond-directional exchange generates strong magnetic frustration and unconventional correlated states. The α, β, γ − Li₂IrO₃ family exhibit fragile and highly anisotropic magnetic behavior, including incommensurate counter-rotating order, strong field sensitivity, and pressure-driven electronic reconstruction. Understanding how chemical substitution perturbs these competing interactions provides a route toward probing the underlying frustrated magnetic state. Here, we study single crystals of β − Li₂Ru_xIr_1−xO₃ with dilute Ru substitution, x ≲ 10%. Through magnetometry, resonant elastic X-ray scattering, ac-heat capacity, and muon spin relaxation/rotation, we show that weak magnetic disorder suppresses the incommensurate antiferromagnetic ground state. Instead, the system evolves into a bulk spin glass characterized by slow relaxation and frozen, local magnetic fields. Despite the loss of long-range order, the glassy state retains substantial directional anisotropy, evidenced by enhanced b-axis magnetic susceptibility and direction-dependent thermoremanent relaxation. Structural probes further indicate that Ru substitution leaves the hyperhoneycomb lattice largely undistorted while disrupting magnetic coherence, suggesting that disorder freezes spins within a still-active bond-directional exchange environment. In this picture, dilute Ru substitution provides a controlled pathway into an anisotropic Kitaev spin glass regime that preserves essential fingerprints of the underlying Kitaev exchange network.

Magnetic pyrochlores with non-Kramers rare-earth ions provide a platform for exploring emergent gauge physics and quantum spin-ice behavior, yet the influence of structural disorder on their ground states remains insufficiently understood. Here we combine bulk characterization and single-crystal neutron-scattering measurements to investigate the non-Kramers pyrochlore Pr2Sn2O7. At temperatures below ∼1 K, the system exhibits key hallmarks of quantum spin-ice physics, including anisotropic spin-ice correlations and two distinct dynamical timescales. Upon further cooling, however, we observe a complete spin-freezing transition at Tf≈0.15 K, accompanied by recovery of the full nuclear Schottky anomaly, the emergence of a gapped magnetic excitation, and the development of incipient (100) magnetic correlations. Comparison with related Pr-based pyrochlores places Pr2Sn2O7 near the spin-frozen boundary of a disorder-perturbed phase diagram. These results establish a disorder-driven framework for the evolution of quantum spin-ice behavior into frozen ground states, revealing how signatures of a proximate quantum spin liquid can persist despite disorder-induced spin freezing in non-Kramers pyrochlores.

Pyrochlore magnets of the form 𝑅₂𝐵₂O₇, in which rare-earth ions on the 𝑅 site form a three-dimensional network of corner-sharing tetrahedra, provide a canonical setting for geometrical frustration. Ho-based pyrochlores host a dipolar spin-ice ground state, characterized by Ising moments constrained by the ice rules and elementary excitations analogous to magnetic monopoles. Here we examine how controlled chemical disorder influences this state by introducing site mixing on the nonmagnetic 𝐵 site in two compounds. Ho₂GaSbO₇ contains only Ga³⁺/Sb⁵⁺ charge disorder, whereas Ho₂ScSbO₇ exhibits both charge and substantial size disorder arising from the large ionic-radius mismatch between Sc³⁺ and Sb⁵⁺. Although both materials retain the pyrochlore structure, neutron-scattering measurements reveal a reduced correlation length for the 𝑅/𝐵-site cation ordering and enhanced local structural distortions in Ho₂ScSbO₇. Despite these structural differences, bulk thermodynamic measurements and magnetic diffuse scattering demonstrate that both systems exhibit the defining signatures of a dipolar spin-ice state. Low-energy inelastic neutron spectroscopy further uncovers broad magnetic excitations that develop within the dipolar spin-ice regime, a feature absent in pristine Ho pyrochlores and indicative of disorder-induced splitting of the non-Kramers ground-state doublet. Together, these results show that controlled disorder generates tunable transverse-field-driven quantum fluctuations in Ho-based pyrochlores, although the dipolar spin-ice state is remarkably robust to this disorder.

The quantum dimer magnet, with antiferromagnetic intradimer and interdimer Heisenberg exchange between spin-1/2 moments, is known to host an $$(\left|\uparrow \downarrow \right\rangle -\left|\downarrow \uparrow \right\rangle )/\sqrt{2}$$singlet ground state when the intradimer exchange is dominant. Rare-earth-based quantum dimer systems with strong spin-orbit coupling offer the opportunity for tuning their magnetic properties by using magnetic anisotropy as a control knob. Here, we present bulk characterization and neutron scattering measurements of the quantum dimer magnet Yb2Be2SiO7. We find that the Yb3+ ions can be described by an effective spin-1/2 model at low temperatures and the system does not show signs of magnetic order down to 50 mK. The magnetization, heat capacity, and neutron spectroscopy data can be well-described by an isolated dimer model with highly anisotropic exchange that stabilizes a singlet ground state with a wavefunction $$(\left|\uparrow \uparrow \right\rangle -\left|\downarrow \downarrow \right\rangle )/\sqrt{2}$$or $$(\left|\uparrow \uparrow \right\rangle+\left|\downarrow \downarrow \right\rangle )/\sqrt{2}$$. Our results show that strong spin-orbit coupling can induce unusual entangled states of matter in quantum dimer magnets.