Observation of Emergent Superconductivity in the Quantum Spin Hall Insulator Ta2Pd3Te5 via Pressure Manipulation

TL;DR

This study reports the emergence of superconductivity in the quantum spin Hall insulator Ta2Pd3Te5 under high pressure, revealing a densified phase that enhances electronic properties and maintains lattice symmetry up to 45 GPa.

Contribution

It provides experimental and theoretical evidence linking pressure-induced structural transitions to superconductivity in a QSH insulator, a novel insight into topological superconductor development.

Findings

Superconductivity appears in Ta2Pd3Te5 at high pressures.

Fermi surface topology changes with pressure, enhancing density of states.

High-pressure phase maintains lattice symmetry up to 45 GPa.

Abstract

Quantum Spin Hall (QSH) insulators possess distinct helical in-gap states, enabling their edge states to act as one-dimensional conducting channels when backscattering is prohibited by time-reversal symmetry. However, it remains challenging to achieve high-performance combinations of nontrivial topological QSH states with superconductivity for applications and requires understanding of the complicated underlying mechanisms. Here, our experimental observations for a novel superconducting phase in the pressurized QSH insulator Ta2Pd3Te5 is reported, and the high-pressure phase maintains its original ambient pressure lattice symmetry up to 45 GPa. Our in-situ high-pressure synchrotron X-ray diffraction, electrical transport, infrared reflectance, and Raman spectroscopy measurements, in combination with rigorous theoretical calculations, provide compelling evidence for the association between the superconducting behavior and the abnormal densified phase. The isostructural transition was found to modify the topology of the Fermi surface directly, accompanied by a fivefold amplification of the density of states at 20 GPa compared to ambient pressure, which synergistically fosters the emergence of robust superconductivity. A profound comprehension of the fascinating properties exhibited by the compressed Ta2Pd3Te5 phase is achieved, highlighting the extraordinary potential of van der Waals (vdW) QSH insulators for exploring and investigating high-performance electronic advanced devices under extreme conditions.