Mechanism of pressure-induced double-dome superconductivity

Determine the underlying mechanism driving the pressure-induced double-dome superconducting phase across the AV3Sb5 family, including chemically doped Cs(V0.86Ta0.14)3Sb5, where competing explanations involve structural phase transitions and pressure-induced electronic or dimensional reconstructions.

Background

High-pressure measurements on Cs(V0.86Ta0.14)3Sb5 reveal two superconducting domes despite the complete suppression of long-range charge density wave order. The paper compares possible explanations across the AV3Sb5 family: structural phase transitions appear near the superconducting minima in KV3Sb5 and RbV3Sb5, whereas CsV3Sb5 retains its lattice symmetry to high pressure and exhibits a pressure-induced dimensional crossover involving interlayer Sb–Sb bonding and reconstruction of Sb-derived bands.

The authors note that the general mechanism responsible for double-dome superconductivity remains unresolved because different members of the family may realize distinct mechanisms. For the Ta-doped compound, they propose that the second dome may arise from a pressure-induced Fermi-surface Lifshitz transition, but the broader microscopic origin of the phenomenon is not established.