THERMOPOWER OF (BI,PB)2SR2CA2CU3OX SINGLE-CRYSTALS UNDER UNIAXIAL-STRESS

We have studied the effect of uniaxial stress sigma11 along the a dire ction, up to 150 MPa, on the thermoelectric power S(sigma11,T) and ele ctrical resistance R(sigma11,T) of (Bi,Pb)2Sr2Ca2Cu3Ox single crystals from the transition temperature to room temperature. Both S and R inc rease monotonically with increasing sigma11. Above T(c), S(sigma11,T) is positive and linear with T, and DELTAS(sigma11,T)/DELTAT=-41 nV/K2 for all sigma11. The extrapolated S(sigma11,T=0) increases with sigma1 1, with DELTAS(sigma11,0)/DELTAsigma11=(1.5+/-0.4)muV K-1 GPa-1. The e ffect of sigma11 on S(sigma11,0) is similar to the effect of a reducti on in the hole density due to annealing under different oxygen atmosph eres. S (sigma11,T) drops sharply at the superconducting transition te mperature T(c)(sigma11). We discuss our results in terms of several re cently proposed models.