Enhanced Superconductivity and Electron Correlations in Intercalated ZrTe$_3$

TL;DR

This study investigates how intercalation in ZrTe₃ enhances superconductivity and electronic correlations by suppressing charge density waves, revealing the role of lattice expansion and Zr valence changes in electronic order formation.

Contribution

It demonstrates the effect of Cu and Ni intercalation on electronic correlations, superconductivity, and lattice structure in ZrTe₃, highlighting the importance of Zr valence states.

Findings

Intercalation suppresses charge density waves in ZrTe₃.

Superconductivity emerges with increased electronic correlations.

Zr valence state shifts from Zr⁴⁺ to Zr²⁺ upon intercalation.

Abstract

Charge density waves (CDWs) with superconductivity, competing Fermi surface instabilities and collective orders, have captured much interest in two-dimensional van der Waals (vdW) materials. Understanding of CDW suppression mechanism, its connection to emerging superconducting state and electronic correlations provides opportunities for engineering the electronic properties of vdW heterostructures and thin film devices. Using combination of the thermal transport, X-ray photoemission spectroscopy, Raman measurements, and first-principle calculations, we observe an increase in electronic correlations of the conducting states as CDW is suppressed in ZrTe$_3$ with 5\% Cu and Ni intercalation in the vdW gap. As superconductivity emerges, intercalation brings decoupling of quasi-one-dimensional conduction electrons with phonons as a consequence of intercalation-induced lattice expansion but also a drastic increase in Zr$^{2+}$ at the expense of Zr$^{4+}$ metal atoms. These observation demonstrate the potential of atomic intercalates in vdW gap for ground state tuning but also illustrate the crucial role of Zr metal valence in formation of collective electronic orders.