Splitting in the Fermi surface of ZrTe_3: a surface charge density wave system

TL;DR

This study uses angle-resolved photoelectron spectroscopy to reveal a surface-induced band splitting in ZrTe_3, linked to structural changes, and investigates the persistence of charge density wave features in the gapped state.

Contribution

It provides the first detailed experimental and theoretical analysis of surface-induced band splitting and its relation to charge density waves in ZrTe_3.

Findings

Band splitting of 100-200 meV observed in ZrTe_3 surface.

Surface structural change causes the band splitting.

Charge density wave features persist in the gapped state.

Abstract

The electronic band structure and Fermi surface of ZrTe_3 was precisely determined by linearly polarized angle-resolved photoelectron spectroscopy. Several bands and a large part of the Fermi surface are found to be split by 100-200 meV into two parallel dispersions. Band structure calculations reveal that the splitting is due to a change of crystal structure near the surface. The agreement between calculation and experiment is enhanced by including the spin-orbit potential in the calculations, but the spin-orbit energy does not lead to a splitting of the bands. The dispersion of the highly nested small electron pocket that gives rise to the charge density wave is traceable even in the low-temperature gapped state, thus implying that the finite correlation length of the long-wavelength modulation leads to a smearing of the band back-folding.