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Title: Intrinsic versus defect-driven phonon thermal Hall effect in SrTiO3
Plain: The effect could come from the phonons themselves or from the way they scatter off impurities. SrTiO3, where it is large, is a clean place to decide.
Precise: For SrTiO3 with $\kappa_{xy}/\kappa_{xx}$ up to $\sim 3e-3$ at $9e4\,\mathrm{G}$ near the $\kappa_{xx}$ maximum, determine whether $\kappa_{xy}$ arises from band-intrinsic phonon chirality (for example involving the soft polar mode and structural domains) or from extrinsic skew scattering, by establishing how $\kappa_{xy}$ scales with $\kappa_{xx}$ and with controlled defect density (oxygen vacancies, isotope substitution).
Settled by: $\kappa_{xy}$ measured on crystals with independently quantified defect density, combined with first-principles phonon Berry curvature for SrTiO3.
Kind: well-posed
Answer type: identification
References: (empty)
Literature status: open
Status note: In SrTiO3 disorder and strain suppress $\kappa_{xy}$ and annealing partly restores it without changing $\kappa_{xx}$ (Xiang et al., npj Quantum Materials 11, 40, 2026, arXiv 2511.08932); the authors read this as an intrinsic lattice effect sensitive to imperfections, not yet tied to a microscopic mechanism.
Posed since: (empty)