Doping evolution of nodal electron dynamics in trilayer cuprate superconductor Bi₂Sr₂Ca₂Cu₃O_10+δ revealed by laser-based angle-resolved photoemission spectroscopy

The doping evolution of the nodal electron dynamics in the trilayer cuprate superconductor Bi₂Sr₂Ca₂Cu₃O_10+δ (Bi2223) is investigated using high-resolution laser-based angle-resolved photoemission spectroscopy (ARPES). Bi2223 single crystals with different doping levels are prepared by controlled annealing, which cover the underdoped, optimally-doped and overdoped regions. The electronic phase diagram of Bi2223 is established which describes the T_c dependence on the sample doping level. The doping dependence of the nodal Fermi momentum for the outer (OP) and inner (IP) CuO₂ planes is determined. Charge distribution imbalance between the OP and IP CuO₂ planes is quantified, showing enhanced disparity with increasing doping. Nodal band dispersions demonstrate a prominent kink at ∼ 94 meV in the IP band, attributed to the unique Cu coordination in the IP plane, while a weaker ∼ 60 meV kink is observed in the OP band. The nodal Fermi velocity of both OP and IP bands is nearly constant at ∼ 1.62 eV⋅Å independent of doping. These results provide important information to understand the origin of high T_c and superconductivity mechanism in high temperature cuprate superconductors.