Collapse of the Pseudogap in Cuprate Superconductors at a Lifshitz Transition
Abstract
We report a fine tuned doping study of strongly overdoped Bi2Sr2CaCu2O8þδ single crystals using
electronic Raman scattering. Combined with theoretical calculations, we show that the doping, at which the
normal-state pseudogap closes, coincides with a Lifshitz quantum phase transition where the active holelike
Fermi surface becomes electronlike. This conclusion suggests that the microscopic cause of the pseudogap is
sensitivetotheFermi surfacetopology.Furthermore,we findthatthe superconductingtransitiontemperatureis
unaffected by this transition, demonstrating that their origins are different on the overdoped side.