Electronic band structure reconstruction in Ni intercalated ZrTe${}_2$

Abstract

The filling of the large van der Waals gap in Transition Metal Dichalcogenides (TMDs) often leads to lattice and electronic instabilities, which prelude the onset of a rich phenomenology. Motivated by previous results from macroscopic measurements, we investigate the electronic structure of the TMDs ZrTe${}_2$ and Ni intercalated ZrTe${}_2$ (Ni${}_x$ZrTe${}_2$, $x\approx 0.05$) employing angle-resolved photoemission spectroscopy (ARPES). We readily identify in Ni${}_x$ZrTe${}_2$ two flat bands, most likely associated with localized Ni-derived 3$d$-states, at about $\approx -0.7$ eV and $\approx -1.2$ eV in binding energy. More significantly, at low $T$, we identify an electronic structure reconstruction in Ni${}_x$ZrTe${}_2$, which halves the electronic periodicity along the $k_z$ direction. This is reminiscent of a commensurate band folding with wave-vector $q=(0,0,\pi )$. A mean-field model for a charge density wave (CDW) transition driven by interband hole-hole interactions is solved with inputs from the experimentally determined electronic band structure. Comparison between theory and experiments unveils a CDW transition in Ni${}_x$ZrTe${}_2$, for which the gap opens above the Fermi level. Our findings invite further investigation into the structural properties of intercalated ZrTe${}_2$.

arXiv comment8 pages, 4 figures, supp material available