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, Tc0 decreases monotonously from 90 K to 60 K, and the pseudogap opening temperature (T*) increases from 163 K to 233 K. The onset temperature (Tv) of vortex-like excitation detected by Nernst effect decreases with decreasing p as Tc0 does. The results suggest that the pseudogap state is divided into two different regimes by the characteristic temperature Tv. The regime between Tc and Tv is dominated by strong phase fluctuations. This temperature regime (Tc0 < T < Tv) is much narrower compared to the underdoped La2-xSrxCuO4