Multicomponent order parameter and penetration depth of YBCO single crystals

We have analyzed the possible temperature variation of the penetration dept h lambda(T) in the(d + s)-wave superconductivity model of hybrid pairing, w hich accounts for the high T-c cuprates with an orthorhombic distortion. Th e slope of the Delta lambda(T) proportional to T for T much less than T-c a nd its dependence on the Delta(s)/Delta(d) admixture in the gap function is analyzed quantitatively. The impurity scattering is taken into account. Re cent measurements of the penetration depth in YBa2Cu3O6.95 single crystals are discussed in terms of this model. (C) 2000 Elsevier Science B.V. All ri ghts reserved.