SPIN-ORBIT SCATTERING AND PAIR BREAKING IN A STRUCTURALLY DISORDERED COPPER-OXIDE LAYER

To leading order in displacement size, the scattering of electrons in a Cu-0 plane from 0 displacements perpendicular to that plane is due to spin-orbit coupling. This scattering is investigated with the following results: (1) As a consequence of time-reversal symmetry, spin fluctuations, which can strongly enhance scattering from a spin impurity, do not enhance spin-orbit scattering; and (2) for a superconductor with a d(x2-y2) gap function, pair breaking from spin-orbit scattering can be strong, particularly in a structurally disordered phase where locally CuO6 octahedra tilt as in the orthorhombic phase of La2CuO4, but globally the average structure is tetragonal. These results are discussed in the context of the (La,Nd)-(Sr,Ba)-Cu-0 system where certain structural transitions axe observed to suppress superconductivity.