Doping-dependent phase diagram of Ca-doped YBCO observed by femtosecond spectroscopy

Y. J. Chen*, Kaung-Hsiung Wu, Chih-Wei Luo, Jiunn-Yuan Lin, Jenh-Yih Juang, T. M. Uen

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


The quasiparticle relaxation dynamics in a single (001) Ca-doped YBCO (Y 0.7Ca 0.3Ba 2Cu 3O 7-δ) superconducting thin film was probed by using the femtosecond timeresolved spectroscopy. The (001) Y 0.7Ca 0.3Ba 2Cu 3O 7-δ thin film was prepared on a (100)STO substrate by pulsed laser deposition. Through controlling the oxygen pressure and the annealing temperature within quartz tube, the doping level (0.08 < p < 0.22) in the phase diagram could be widely tuned from the overdoped region to the underdoped region with varying the hole concentration (p) in a single sample. In the overdoped region, two different components (positive/negative) were obviously identified in the transient reflectivity curves (ΔR/R). The negative component in ΔR/R emerges at T < T c and quickly defeated by the development of the positive component. The dramatic change in the positive component of ΔR/R arises well below T c. However, this anomaly change does not appear in the underdoped region. Only the positive ΔR/R was clearly observed at whole temperatures. These results indicate that the scenario of high-T c superconductivity in the overdoped region would be different from the underdoped region.

Original languageEnglish
Pages (from-to)515-517
Number of pages3
JournalJournal of Superconductivity and Novel Magnetism
Issue number1-2
StatePublished - 1 Jan 2011


  • Cuprate superconductors
  • Nernst effect
  • Ultrafast spectroscopy


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