Splitting in the Fermi surface of ZrTe3 : A surface charge density wave system

The electronic band structure and Fermi surface of ZrTe3 was determined by angle-resolved photoemission spectroscopy. Several bands and a large part of the Fermi surface are found to be split by 100–200 meV into two parallel dispersions. Calculations of the bulk band structure cannot reproduce this splitting even if spin-orbit interaction is taken into account. A bilayer model representing the top layers of a surface-relaxed structure without reconstruction introduces the observed splitting and reproduces most features observed in the data thus suggesting a surface relaxation of the freshly cleaved ZrTe3. 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 and the gap energy is determined as εg=65±10 meV