Disorder-induced proximate quantum spin ice phase in Pr₂Sn₂O₇

Magnetic pyrochlores with non-Kramers ground-state doublets provide a rich setting for exploring emergent gauge physics and quantum spin-liquid (QSL) systems. Increasing evidence suggests that disorder plays a decisive role in determining their low-temperature magnetic dynamics. I will present a comprehensive bulk and neutron-scattering study of single-crystalline Pr₂Sn₂O₇, a non-Kramers pyrochlore synthesized by flux growth. Unpolarized neutron diffuse scattering reveals the onset of spin-ice correlations below 1 K, characterized by anisotropic pinch-point features consistent with quantum spin-ice (QSI) behavior. A.C. susceptibility measurements show a progressive slowing of spin dynamics in this regime, culminating in complete spin freezing below 0.15 K. Inelastic neutron spectroscopy at 0.5 K uncovers a broad quasi-elastic spectrum whose low-energy intensity (0–0.2 meV) is strongly suppressed upon cooling through the freezing temperature, while an incipient (100) magnetic order and a gapped excitation near 0.23 meV persist, consistent with a spin-freezing transition driven by condensation of vison excitations [1]. Two distinct dynamical time scales, a slow component (~10⁻⁵ s) and a fast component (~10⁻¹⁰ s), emerge above the freezing temperature, in quantitative agreement with theoretical expectations for QSI dynamics [2]. Together, these results indicate that Pr₂Sn₂O₇ enters a disorder-induced spin-frozen phase driven by confinement of vison excitations, placing its ground state in close proximity to the U(1) QSL regime.

[1] G. Chen, Phys. Rev. B 94, 205107 (2016).

[2] B. Tomasello, C. Castelnovo, R. Moessner, and J. Quintanilla, Phys. Rev. Lett. 123, 067204 (2019).