Tuning Superconductivity and Charge Density Wave Order in 2H-TaSe2 by Modulating the Van Hove Singularity

TL;DR

This study demonstrates that electron doping in 2H-TaSe2 via Pt substitution can tune the Van Hove singularity near the Fermi level, suppress charge density waves, and enhance superconductivity, revealing new ways to control electronic states.

Contribution

It introduces a method to tune the Van Hove singularity in TaSe2 through chemical doping, affecting charge density wave and superconducting properties.

Findings

VHs moved closer to Fermi level with doping

Charge density wave suppressed in doped samples

Superconducting temperature increased to ~2.7 K

Abstract

Tantalum diselenide (TaSe2) is an exciting material that hosts charge density wave order (CDW) and superconductivity. Thus, providing a playing field for examining the interactions of fundamental electronic quantum states in materials. Recent research has proposed that the intrinsic quantum electronic state in the TaSe2 lattice could be improved by aligning the Van Hove singularity (VHs) with the Fermi level. In this study, we attempt to tune the VHs in TaSe2 to align them within the vicinity of the Fermi level via electron doping by chemically substituting Pt for Ta atoms. On investigating the band structure of Pt0.2Ta0.8Se2, the electron doping brought the VHs closer to the Fermi level vicinity around the K high symmetry point. As a result, the CDW state in pristine TaSe2 is suppressed in the TaSe2 doped system while also hosting an enhanced superconducting temperature (Tc) of ~2.7 K. These observations provide insight into ways to leverage the VHs in materials to tune their electronic properties.