paper

Origin of the charge density wave state in BaFeAl

arXiv:2410.22734 · doi:10.1103/PhysRevB.110.195118

Abstract

Recently, a first-order phase transition associated with charge density wave (CDW) has been observed at low temperatures in intermetallic compound BaFeAl. However, this transition is absent in its isostructural sister compound BaCoAl. Consequently, an intriguing question arises as to the underlying factors that differentiate BaFeAl from BaCoAl and drive the CDW transition in BaFeAl. Here, we set out to address this question by conducting a comparative \emph{ab initio} study of the electronic structures, lattice dynamics, \textcolor{black}{and electron-phonon interactions} of their high-temperature phases. We find that both compounds are dynamically stable with similar phonon dispersions. The electronic structure calculations reveal that both compounds are nonmagnetic metals; however, they exhibit distinct band structures around the Fermi level. In particular, BaFeAl exhibits a higher density of states at the Fermi level with dominant partially filled Fe- states and a more intricate Fermi surface. This leads to an electronic instability of BaFeAl toward the CDW transition, which is manifested by the diverged electronic susceptibility at the CDW wave vector =(0.5, 0, 0.3), observable in both the real and imaginary parts. Conversely, BaCoAl does not display such behavior, aligning well with experimental observations. Although the electron-phonon interactions in BaFeAl surpass those in BaCoAl by two orders of magnitude, the strength is relatively weak at the CDW wave vector, suggesting that the CDW in BaFeAl is primarily driven by electronic factors.

9 pages, 6 figures

References in corpus (7)