Abstract
In one-dimensional quantum materials, electrons and lattices can undergo a Peierls transition, a translational symmetry-breaking instability traditionally understood through electron coupling to longitudinal acoustic phonons. Recently, this paradigm has been revised in topological semimetals, where transverse acoustic phonons couple to p-orbital electrons, giving rise to a transverse Peierls transition. Importantly, transverse Peierls transition-induced distortions can further break mirror or inversion symmetries, producing nematic or chiral charge density waves. Here, we report the experimental identification of an incommensurate transverse Peierls transition in EuAl4. Using meV-resolution inelastic x-ray scattering, we observe complete softening of a transverse acoustic phonon upon cooling, while the longitudinal acoustic mode remains unaffected. First-principles calculations reveal that the transverse Peierls transition wavevector coincides with a charge susceptibility peak connecting nested Dirac bands. Second harmonic generation confirms mirror symmetry breaking, supporting a chiral charge density wave stabilized by the transverse Peierls transition.
| Original language | English |
|---|---|
| Article number | 10401 |
| Journal | Nature Communications |
| Volume | 16 |
| Issue number | 1 |
| DOIs | |
| State | Published - Dec 2025 |
Funding
We thank Juba Bouaziz, Stefan Blügel, Cristian Batista, Andrew Christianson, Satoshi Okamoto and Yang Zhang for stimulating discussions. This research was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division (X-ray, sample growth, microscopy, and theory). X-ray scattering used resources (beamline 4ID and 30ID) of the Advanced Photon Source, a U.S. DOE Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357 and resources (beamline 4-ID) of the National Synchrotron Light Source II, a US Department of Energy Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory under contract no. DE-SC0012704. Pat of the microscopy was supported by a DOE-BES Early Career project FWP #ERKCZ55 (H.N.). Microscopy experiment was performed at the ORNL’s Center for Nanophase Materials Sciences (CNMS), which is a DOE Office of Science User Facility. L. Z. acknowledges the support by the National Science Foundation through the Materials Research Science and Engineering Center at the University of Michigan, Award No. DMR-2309029. K.F.L. acknowledges the Texas Advanced Computing Center at The University of Texas at Austin for providing access to Frontera, Stampede3, and Lonestar6 ( http://www.tacc.utexas.edu ).