Disorder Quenching of the Charge Density Wave in ${\mathrm{ZrTe}}_3$

The charge density wave (CDW) in ${\mathrm{ZrTe}}_3$ is quenched in samples with a small amount of Te isoelectronically substituted by Se. Using angle-resolved photoemission spectroscopy we observe subtle changes in the electronic band dispersions and Fermi surfaces upon Se substitution. The scattering rates are substantially increased, in particular for the large three-dimensional Fermi surface sheet. The quasi-one-dimensional band is unaffected by the substitution and still shows a gap at low temperature, which starts to open from room temperature. Long-range order is, however, absent in the electronic states as in the periodic lattice distortion. The competition between superconductivity and the CDW is thus linked to the suppression of long-range order of the CDW.

Figure 1

FS maps of ${\mathrm{ZrTe}}_3$ (a) and ${\mathrm{ZrTe}}_{2.96}{\mathrm{Se}}_{0.04}$ (c), acquired by ARPES at a temperature $T=7\mathrm{K}$. The inset shows one unit cells of the crystal lattice of ${\mathrm{ZrTe}}_3$ projected onto the $(a,c)$ planes and the Brillouin zone. The nearly equidistant Te chains adjacent to the van der Waals gap are highlighted by gray bars. Panels (b) and (d) show momentum distribution curves extracted from the maps along straight lines along $k_y$ at two different $k_x$.

Figure 2

ARPES dispersion cuts for ${\mathrm{ZrTe}}_3$ (a)–(d) and ${\mathrm{ZrTe}}_{2.96}{\mathrm{Se}}_{0.04}$ (e)–(h) at $T=7\mathrm{K}$. Red dots in panels (a),(b),(e),(f) show the peak positions determined by numerical fits. A detailed view of these peak positions for the q1D bands along $k_x$ close to $\overline{B}$ is shown in panel (k). Energy distribution curves at high symmetry points are shown in (i) for $\overline{B}$ and in (j) for $\overline{D}$ for both samples. Dashed lines in panel (k) are drawn following the intensity traces in panels (b),(f) as a guide to the eye.

Figure 3

Extracted peak widths at $T=7\mathrm{K}$ from fits to MDCs as a function of $E$ for both samples. The corresponding peak positions are shown in Fig. 2. Panel (a) shows the 3D band along $\mathrm{\Gamma }-Y$, at $k_y=0$. Panel (b) shows the 3D band along $\mathrm{\Gamma }-B$, at $k_x=0$. Panel (c) shows the q1D band along $k_y$ for $k_x=0.2{\AA }^{-1}$ and (d) near $\overline{D}$.

Figure 4

Temperature dependence of the photoemission intensity at $E_F$ from ${\mathrm{ZrTe}}_3$ (a) and ${\mathrm{ZrTe}}_{2.96}{\mathrm{Se}}_{0.04}$ (b). The intensities are summed up over a small range of $0.4<k_y<0.67{\AA }^{-1}$ at three different positions of $k_x$ as indicated.