Momentum-dependent charge-density-wave gap formation in ZrTe_{2.98}Se_{0.02}

TL;DR

This study uses laser photoemission microscopy to analyze the momentum-dependent energy gap formation associated with charge density waves in ZrTe_{2.98}Se_{0.02}, revealing the roles of Fermi surface nesting and electron-phonon interactions.

Contribution

It provides detailed momentum-resolved insights into the CDW gap formation and highlights the combined influence of Fermi surface nesting and band-dependent electron-phonon coupling.

Findings

CDW gap forms in a specific momentum region along the BZ boundary.

The gap formation correlates with a quasi-one-dimensional Fermi surface.

Both Fermi surface nesting and electron-phonon coupling are crucial for understanding the CDW state.

Abstract

We investigated the energy gap formation across the charge density wave (CDW) transition inof ZrTe_{2.98}Se_{0.02}. By employing a laser photoemission microscopy, we clearly resolved one elliptical Fermi surface (FS) around the Brillouin zone (BZ) center, and two quasi-one-dimensional FSs along the BZ boundary. We further mapped the intensity difference between the FSs below and above the CDW transition temperature. We found that the energy CDW gap formation is limited to the momentum region 0.25 {\AA}^{-1} < ky < 0.8 {\AA}^{-1} along \bar{B}-\bar{D} line, which coincides with the location of one of the quasi-one-dimensional FSs. Characteristic momentum dependence in the energy CDW gap suggests the importance of both FS nesting and band-dependent electron-phonon coupling for understanding the CDW state in ZrTe_{3} system.