COUPLING OF THE ORTHORHOMBIC DISTORTION TO THE DEPRESSION OF THE Tc'S DUE TO Zn2+ DOPING IN THE "RE-123" HTSC'S: A (d+s)-WAVE PICTURE

Abstract

The depressions of the T c 's of the "123" REBa 2 Cu 3 O 7 HTSC's due to the substitution of Zn 2+ 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 T c 's caused by Zn 2+ substitution into the CuO 2 is due to a reduction of the SF-mediated pairing interaction. The differences in the rates of suppression of T c due to Zn 2+ 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.