Coupling of the orthorhombic distortion to the depression of the T<inf>c</inf>'s due to Zn²⁺doping in the "re-123" HTSC's: A (d + s)-wave picture

Abstract

The depressions of the Tc's of the "123" REBa2Cu3O7HTSC's due to the substitution of Zn2+ions into the Cu(2) layer are studied. The orthorhombic distortion which occurs in the "123" ceramics is assumed to induce a modification to the spin-fluctuation (SF) mediated pairing interaction which inturn causes the order parameters of these HTSC's to be of mixed (d + s)-wave symmetry. It is shown that part of the rapid depression of the Tc's caused by Zn2+substitution into the CuO2is due to a reduction of the SF-mediated pairing interaction. The differences in the rates of suppression of Tcdue to Zn2+doping in the different "RE-123" HTSC's are shown to be due to the changes in the orthorhombicity which depend on the size of the rare earth ions. © World Scientific Publishing Company.