CM In the literature: open

Intrinsic versus defect-driven phonon thermal Hall effect in SrTiO3

In plain words

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 statement

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).

What would settle it

$\kappa_{xy}$ measured on crystals with independently quantified defect density, combined with first-principles phonon Berry curvature for SrTiO3.

Status in the literature

Unverified 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.