Pressure-tuned double-dome superconductivity in KZnBi with honeycomb lattice

TL;DR

This study reports a pressure-induced double-dome superconducting phase in KZnBi with a honeycomb lattice, revealing complex phase transitions and topological electronic states that enhance understanding of superconductivity in such materials.

Contribution

It uncovers a novel pressure-tuned double-dome superconducting behavior and topological phase transition in KZnBi, expanding the knowledge of honeycomb lattice superconductors.

Findings

Superconducting Tc reaches 7 K at 2.5 GPa

Reentrant superconductivity with Tc of 8 K near 7 GPa

Transition from Dirac band to topological semimetal state

Abstract

Materials with honeycomb lattice structures exhibit unique electronic properties arising from their distinctive atomic arrangements. Their weakly coupled nature facilitates modulation by external stimuli, which leads to a diverse range of physical phenomena, particularly superconductivity. Here, we report the discovery of a pressure-induced M-shaped double-dome superconducting phase in KZnBi with honeycomb lattice. Under applied pressure, the superconducting transition temperature Tc increases sharply and reaches a maximum value of 7 K at approximately 2.5 GPa. Following a structural phase transition from the ambient-pressure P63/mmc phase to the high-pressure Pnma phase, Tc gradually decreases. Further compression induces an electronic transition near 7 GPa, accompanied by an unexpected reentrant superconducting phase with a higher Tc of 8 K. Our theoretical calculations indicate that KZnBi undergoes a transition from a Dirac band structure to a strong topological semimetal state following the structural phase transition. These findings establish KZnBi as an ideal platform for investigating the diverse structural manifestations and intrinsic phenomena of the honeycomb lattice, demonstrating the fundamental importance of honeycomb structures in advancing superconductivity research.