Direct observation of the coexistence of the pseudogap and superconducting quasiparticles in Bi2Sr2CaCu2O8+y by time-resolved optical spectroscopy
Direct observation of the coexistence of the pseudogap and superconducting quasiparticles in Bi2Sr2CaCu2O8+y by time-resolved optical spectroscopy
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DOI：
10.1103/physrevlett.101.137003
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发表时间：
2008-09-26
影响因子：
8.6
通讯作者：
Ido, M.
中科院分区：
文献类型：
--
作者：
Liu, Y. H.;Toda, Y.;Ido, M.
报道了用时间分辨泵浦-探测技术测量的欠掺杂Bi_2Sr_2CaCu_2O_（8 +y）（Bi_（2212））单晶准粒子在赝能隙（PG）态和超导（SC）态的超快光学响应.在探测能量hw（pr）= 1.55 eV时，发现反射率变化Δ R/R在T-c处改变其符号，这允许直接分离PG和SC QP的电荷动力学。进一步的系统研究表明，与PG和SC QP相关的瞬态信号依赖于探测光束的能量和偏振。通过将它们调谐到低于T-c，可以同时检测到两种不同的组分，为PG和SC QP的共存提供证据。
We report the ultrafast optical response of quasiparticles (QPs) in both the pseudogap ( PG) and superconducting (SC) states of an underdoped Bi2Sr2CaCu2O8+y (Bi2212) single crystal measured with the time-resolved pump-probe technique. At a probe energy hw(pr) = 1.55 eV, it is found that the reflectivity change Delta R/R changes its sign at exactly T-c, which allows the direct separation of the charge dynamics of PG and SC QPs. Further systematic investigations indicate that the transient signals associated with PG and SC QPs depend on the probe beam energy and polarization. By tuning them below T-c, two distinct components can be detected simultaneously, providing evidence for the coexistence of PG and SC QPs.