paper

Phonon thermal Hall effect in a metallic spin ice

arXiv:2202.12149 · doi:10.1038/s41467-022-32375-0

Abstract

It has become common knowledge that phonons can generate thermal Hall effect in a wide variety of materials, although the underlying mechanism is still controversial. We study longitudinal $I^º_{xx}$ and transverse $I^º_{x y}$ thermal conductivity in Pr $_{2}$ Ir $_{2}$ O $_{7}$ , which is a metallic analogue of spin ice. Despite the presence of mobile charge carriers, we find that both $I^º_{xx}$ and $I^º_{x y}$ are dominated by phonons. A $T / H$ scaling of $I^º_{xx}$ unambiguously reveals that longitudinal heat current is substantially impeded by resonant scattering of phonons on paramagnetic spins. Upon cooling, the resonant scattering is strongly affected by a development of spin ice correlation and $I^º_{xx}$ deviates from the scaling in an anisotropic way with respect to field directions. Strikingly, a set of the $I^º_{xx}$ and $I^º_{x y}$ data clearly shows that $I^º_{x y}$ correlates with $I^º_{xx}$ in its response to magnetic field including a success of the $T / H$ scaling and its failure at low temperature. This remarkable correlation provides solid evidence that an indispensable role is played by spin-phonon scattering not only for hindering the longitudinal heat conduction, but also for generating the transverse response.

18 pages, 4 figures