Dependence of superconducting and pseudogap quasiparticle dynamics on the number of CuO2 planes in Bi-based cuprate superconductors

Abstract

The maximum superconducting transition temperature Tc,max in cuprate superconductors exhibits a strong dependence on the number of CuO2 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 Bi2Sr2Can−1CunO2n+4+δ (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 UdSC for all three compounds follow a universal scaling with Tc2, 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 Tc,max in trilayer cuprates is accompanied by a robust pseudogap.

Source-reported materials — not catalogue approval

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