The maximum superconducting transition temperature $T_{c,\max }$ in cuprate superconductors exhibits a strong dependence on the number of ${\mathrm{CuO}}_2$ planes $n$ per structural cell, exceeding 100 K in trilayer compounds ($n=3$). Elucidating the mechanism responsible for this enhancement of superconductivity in trilayer systems is therefore a central issue. Here we investigate the quasiparticle dynamics of optimally doped Bi-based cuprates ${\mathrm{Bi}}_2{\mathrm{Sr}}_2{\mathrm{Ca}}_{n-1}{\mathrm{Cu}}_n{\mathrm{O}}_{2n+4+\delta }$ ($n=1–3$), using time-resolved pump-probe reflectivity measurements, with particular focus on the trilayer Bi2223 ($n=3$). In all compounds, the transient reflectivity reveals two characteristic components: a slow superconducting (SC) response and a fast pseudogap (PG) response with opposite signs under our probe conditions. These responses exhibit a distinct and systematic temperature evolution depending on $n$. The photoinduced SC phase depletion energy densities $U_d^{\mathrm{SC}}$ for all three compounds follow a universal scaling with $T_c^2$, whereas the energy density required for PG suppression in Bi2223 is found to be approximately three times larger than the values for La-Bi2201 and Bi2212. These results provide bulk-sensitive evidence that the enhancement of $T_{c,\max }$ in trilayer cuprates is accompanied by a robust pseudogap.

Close

PrevNext

View figure in article

• Pseudogap
• Superconductivity
• Cuprates
• High-temperature superconductors
• Time-resolved reflection spectroscopy
• Ultrafast pump-probe spectroscopy