Thickness-dependent anisotropic superconductivity and charge density wave in ZrTe3 down to the two-dimensional limit

Abstract

Reduced thickness could have dramatic impact on the dynamic ordering kinetics and the electronic structures in two-dimensional materials. Here we focus on ZrTe3, a quasi-one-dimensional charge-density-wave system that can transform into a mixed bulk-filament anisotropic superconducting state with the superconducting transition temperature (Tczero) of 1.6 K. We have successfully exfoliated ZrTe3 crystal from bulk crystal to bilayer (2 nm) flake. By examining the anisotropic transport properties, we reveal a competitive relationship between superconductivity and charge density wave (CDW) in the thickness range down to 8 nm. With decreasing thickness, superconductivity is enhanced (yielding a maximum Tczero of about 5 K at 18 nm) while CDW is suppressed. Upon further decreasing thickness, an unexpected enhancement on CDW transition temperature was observed accompanied with the superconductivity rapidly suppressing and finally vanishing. Shifting of Fermi level upon thinning, anisotropic strain from the substrates, and the increase of disorder scattering as approaching the two-dimensional limit might be taken into account for understanding these behaviors. The nonmonotonic evolution with a reduction of thickness is rare and may indicate an intricate mechanism of CDW and SC in ZrTe3.

Source-reported materials — not catalogue approval

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