Origin of Charge Density Wave in SrAl4 and EuAl4

Scientific Achievement

First-principles calculations successfully explain the presence and absence of charge density wave (CDW) across

Charge Density Wave SrAI4
Charge density wave (CDW) in SrAl4 and EuAl4 but not BaAl4. (a) Real part of bare susceptibility function (Re๐œ’๐‘žฯ‡(q)) and phonon life-time (๐›พ๐‘žฮณ_q) along ฮ“ฮ“-Z, (b) phonon dispersion of the transverse acoustic (TA) mode, and (c) charge density difference.

the topological semimetal series (Sr, Ba, Eu)Al4.

Significance and Impact

This study reveals the different roles that Fermi surface nesting (FSN) and electron-phonon coupling (EPC) play to drive CDW, which broadens the understanding and use of CDW to modulate electronic properties of topological semimetals.

Research Details
  • 3D susceptibility function and EPC have been calculated from Wannier functions and density-functional perturbative theory.
  • Although all three compounds have similar FSN from Re๐œ’๐‘žฯ‡(q), the larger EPC at small q-vector in SrAl4 and EuAl4 than BaAl4 drives the CDW, explaining the experimental observations.
  • The predicted transverse acoustic mode softening for such CDW is confirmed in a recent experiment.
    ย 

L.-L. Wang, N. K. Nepal, P. C. Canfield, โ€œOrigin of charge density wave in topological semimetals SrAl4 and EuAl4,โ€
Commun Phys 7, 111 (2024) https://doi.org/10.1038/s42005-024-01600-1