THEORY OF LOCAL-DENSITY OF STATES OF D(X(2)-Y(2))-WAVE SUPERCONDUCTING STATE NEAR THE SURFACES OF THE T-J MODEL

Spatial dependencies of the pair potential and the local density of st ates near the surfaces of d(x2-y2)-wave superconductors are studied th eoretically. The calculation is based on the t-J model within a mean-f ield theory with Gutzwiller approximation. Various types of surface ge ometries are considered. Similar to our result in the extended Hubbard model, it is found that the formation of zero-energy states strongly depends on the surface geometry. In addition to this feature, the zero -energy states give peak splitting for the (110) surfaces when the sup er-exchange interaction J is large. This is due to the induced s-wave component near the surface. The present result explains the microscopi c origin of the spontaneous time-reversal symmetry breaking at the sur faces of high-T-c superconductors.