Phonon thermal Hall effect in a metallic spin ice

• Published in: Nature communications 2022-08, Vol.13 (1), p.4604-8, Article 4604
• Main Authors: Uehara, Taiki, Ohtsuki, Takumi, Udagawa, Masafumi, Nakatsuji, Satoru, Machida, Yo
• Format: Article
• Language: English
• Subjects: 639/766/119/995; 639/766/119/997; CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; Conduction heating; Conductive heat transfer; Correlation; Current carriers; Electromagnetism; electronic properties and materials; Hall effect; Heat; Humanities and Social Sciences; Ice; Low temperature; Magnetic fields; magnetic properties and materials; MATHEMATICS AND COMPUTING; multidisciplinary; Phonons; Scaling; Scattering; Science; Science (multidisciplinary); Spin ice; Temperature gradients; Thermal conductivity; Thermal response
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-022-32375-0

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 κ x x and transverse κ x y thermal conductivity in Pr 2 Ir 2 O 7 , which is a metallic analog of spin ice. Despite the presence of mobile charge carriers, we find that both κ x x and κ x y are dominated by phonons. A T / H scaling of κ x x 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 κ x x deviates from the scaling in an anisotropic way with respect to field directions. Strikingly, a set of the κ x x and κ x y data clearly shows that κ x y correlates with κ x x 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. The thermal Hall effect, or a temperature gradient transverse to a heat current and a magnetic field, has been observed in many materials, but its mechanism is not fully understood. Uehara et al. demonstrate the dominant phonon contribution to both longitudinal and transverse thermal response in a metallic spin ice Pr 2 Ir 2 O 7 .