Lifshitz transition enabling superconducting dome around a charge-order critical point

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Critical Phenomena

Background:

• Superconductivity frequently appears near magnetic quantum critical points (QCPs).
• The link between superconductivity and charge-order QCPs is poorly understood, yet crucial for high-temperature superconductors.
• Titanium diselenide is a material exhibiting charge-density-wave order.

Purpose of the Study:

• To investigate the emergence of superconductivity around a charge-density-wave QCP in titanium diselenide.
• To elucidate the mechanism driving superconductivity in relation to Fermi surface topology changes.
• To explore the role of charge fluctuations in unconventional superconductivity.

Main Methods:

• Electrical resistance measurements under hydrostatic pressure.
• Quantum oscillation measurements.
• Electronic structure calculations.
• Analysis of Fermi surface topology and Lifshitz transitions.

Main Results:

• A dome of superconductivity was observed surrounding the charge-density-wave QCP in titanium diselenide.
• Superconductivity onset correlates with the sudden appearance of large electron and hole pockets (Lifshitz transition).
• Evidence suggests unconventional s± superconductivity mediated by charge-density-wave fluctuations.

Conclusions:

• Charge-density-wave fluctuations and associated Lifshitz transitions are key to unconventional superconductivity in titanium diselenide.
• This work highlights the critical role of the electronic ground state and charge fluctuations in enabling exotic superconducting phases.
• Findings provide insights into mechanisms relevant to high-temperature superconductivity and other correlated electron systems.