Sizable Suppression of Thermal Hall Effect upon Isotopic Substitution in SrTiO_{3}.

摘要: We report measurements of the thermal Hall effect in single crystals both pristine and isotopically substituted strontium titanate. discovered a 2 orders magnitude difference conductivity between ${\mathrm{SrTi}}^{16}{\mathrm{O}}_{3}$ $^{18}\mathrm{O}$-enriched ${\mathrm{SrTi}}^{18}{\mathrm{O}}_{3}$ samples. In most temperature ranges, (${\ensuremath{\kappa}}_{xy}$) is proportional to longitudinal (${\ensuremath{\kappa}}_{xx}$), which suggests phonon-mediated effect. However, they deviate their maxima, angle ratio ($|{\ensuremath{\kappa}}_{xy}/{\ensuremath{\kappa}}_{xx}|$) shows anomalously decreasing behavior below ferroelectric Curie ${T}_{c}\ensuremath{\sim}25\text{ }\text{ }\mathrm{K}$. This observation new underlying mechanism, as conventional scenario cannot explain such differences within slight change phonon spectrum. Notably, rapidly correlated with strength quantum critical fluctuations this displacive ferroelectric. relation points link physics titanate its effect, possible clue example an exotic phenomenon nonmagnetic insulating systems.