The spatially resolved relaxation characteristics of photoinduced quasiparticles (QPs) in CuO2 planes of underdoped YBCO are disclosed by polarized fs time-resolved spectroscopy. The relaxation time (τ) along b axis diverges at Tc, and appears to be governed by a temperature-dependent gap Δ(T) at T<Tc. Furthermore, for T>Tc, a monotonic increase of τ with decreasing T along the b axis and ab diagonal was observed and can be attributed to a temperature-independent gap Δp. The results lend support to the recombination dominant scenario of QP dynamics. However, the QP thermalization may take part along the nodal direction in the highly underdoped samples.
|Number of pages||4|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - 15 Sep 2005|