Superconductivity and Charge Density Wave in ZrTe${}_{3-x}$Se${}_x$

Abstract

Charge density wave (CDW), the periodic modulation of the electronic charge density, will open a gap on the Fermi surface that commonly leads to decreased or vanishing conductivity. On the other hand superconductivity, a commonly believed competing order, features a Fermi surface gap that results in infinite conductivity. Here we report that superconductivity emerges upon Se doping in CDW conductor ZrTe${}_3$ when the long range CDW order is gradually suppressed. Superconducting critical temperature $T_c(x)$ in ZrTe${}_{3-x}$Se${}_x$ ($0\le x\le 0.1$) increases up to 4 K plateau for $0.04$$\le$$x$$\le$$0.07$. Further increase in Se content results in diminishing $T_c$ and filametary superconductivity. The CDW modes from Raman spectra are observed in $x$ = 0.04 and 0.1 crystals, where signature of ZrTe${}_3$ CDW order in resistivity vanishes. The electronic-scattering for high $T_c$ crystals is dominated by local CDW fluctuations at high temperures, the resistivity is linear up to highest measured $T=300K$ and contributes to substantial in-plane anisotropy.

15 pages, 4 figures