Nernst effect in oxygen-depleted SmBa2Cu3O6+x single crystals

The transport properties and Nernst effect of underdoped SmBa2Cu3O6+x single crystals were measured. As hole concentration p decreases from 0.142 to 0.096, T-c0 decreases monotonously from 90 K to 60 K, and the pseudogap opening temperature (T*) increases from 163 K to 233 K. The onset temperature (T-v) of vortex-like excitation detected by Nernst effect decreases with decreasing p as T-c0 does. The results suggest that the pseudogap state is divided into two different regimes by the characteristic temperature Tv. The regime between T-c and T-v is dominated by strong phase fluctuations. This temperature regime (T-c0 < T < T-v) is much narrower compared to the underdoped La2-xSrxCuO4. (c) 2007 Elsevier B.V. All rights reserved.