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arXiv · 2007.05088

Thermal Hall conductivity in the cuprate Mott insulators Nd$_2$CuO$_4$ and Sr$_2$CuO$_2$Cl$_2$

Marie-Eve Boulanger·Gaël Grissonnanche·Sven Badoux·Andréanne Allaire·Étienne Lefrançois·Anaëlle Legros·Adrien Gourgout·Maxime Dion·C. H. Wang·X. H. Chen·R. Liang·W. N. Hardy·D. A Bonn·Louis Taillefer
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Abstract

The heat carriers responsible for the unexpectedly large thermal Hall conductivity of the cuprate Mott insulator La$_2$CuO$_4$ were recently shown to be phonons. However, the mechanism by which phonons in cuprates acquire chirality in a magnetic field is still unknown. Here, we report a similar thermal Hall conductivity in two cuprate Mott insulators with significantly different crystal structures and magnetic orders - Nd$_2$CuO$_4$ and Sr$_2$CuO$_2$Cl$_2$ - and show that two potential mechanisms can be excluded - the scattering of phonons by rare-earth impurities and by structural domains. Our comparative study further reveals that orthorhombicity, apical oxygens, the tilting of oxygen octahedra and the canting of spins out of the CuO$_2$ planes are not essential to the mechanism of chirality. Our findings point to a chiral mechanism coming from a coupling of acoustic phonons to the intrinsic excitations of the CuO$_2$ planes.

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Marie-Eve Boulanger, Gaël Grissonnanche, Sven Badoux, Andréanne Allaire, Étienne Lefrançois, Anaëlle Legros, Adrien Gourgout, Maxime Dion, C. H. Wang, X. H. Chen, R. Liang, W. N. Hardy, D. A Bonn, Louis Taillefer. 2020-07-09. Thermal Hall conductivity in the cuprate Mott insulators Nd$_2$CuO$_4$ and Sr$_2$CuO$_2$Cl$_2$. https://doi.org/10.1038/s41467-020-18881-z

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