Daily Overview: Today’s highlighted work focuses on the significant enhancement of the phonon thermal Hall effect by density-wave order in the trilayer Ruddlesden–Popper nickelate La₄Ni₃O₁₀. The study reveals that upon the density-wave phase transition at around 140 K, the phonon thermal Hall response increases sharply: the thermal Hall angle rises from 1.5‰ at 160 K to over 6‰, and the thermal Hall resistivity exhibits a double-plateau feature. By comparing with the magnon–phonon dispersion crossing energy, it is confirmed that magnon–phonon hybridization induced by spin-density-wave order is the central mechanism behind this effect. This discovery uncovers strong spin–lattice coupling that governs phonon transport in nickelates, and suggests that such dynamic coupling may participate in suppressing antiferromagnetic order and promoting the emergence of superconductivity under high pressure through the softening of optical phonons, thereby offering a new perspective for understanding the cooperative evolution of charge, spin, and lattice degrees of freedom in unconventional superconductors. arXiv submission processing window: 2026-06-24 00:00 to 2026-06-24 00:00 UTC.

1. Density-wave order enhances the phonon thermal Hall effect in a trilayer nickelate

Summary: In the ambient-pressure normal state of the trilayer Ruddlesden-Popper nickelate La₄Ni₃O₁₀, researchers observed a phonon thermal Hall effect enhanced by density-wave order. The material undergoes a density-wave transition at about 140 K, below which the thermal Hall response sharply increases; the thermal Hall angle rises from 1.5‰ at 160 K to 6‰ near 100 K, peaks at ~7‰ at 70 K, and two distinct plateaus appear in the thermal Hall resistivity. The longitudinal thermal conductivity shows almost no magnetic field dependence and has a negligible electronic contribution, confirming that phonons dominate both longitudinal and transverse thermal transport. The characteristic energy extracted from thermal Hall data is about 4.1 meV, which closely matches the magnon–phonon dispersion crossing energy of 3.2 meV, indicating that magnon–phonon hybridization induced by spin-density-wave order is the core mechanism enhancing the thermal Hall effect. This work reveals the significant modulation of phonon transport by spin–lattice coupling in nickelates and points out that such dynamic coupling may participate in suppressing antiferromagnetic order and promoting superconductivity under high pressure via softening of optical phonons, providing a new perspective for understanding the intertwining of charge, spin, and lattice degrees of freedom in unconventional superconductors.