IMPURITY SCATTERING IN VORTEX STATES OF D-WAVE SUPERCONDUCTOR

Earlier we have shown that in a magnetic field (B) over right arrow pa rallel to (c) over right arrow the square lattice tilted by 45 degrees from the a axis is most stable except in the immediate vicinity of T- c, the superconductivity transition temperature. Here we report recent results of the effect of impurities on the vortex state. We find 1) u nlike in the ordinary s-wave superconductor the upper critical field d ecreases in the presence of impurities. 2) the square lattice is rathe r stable even in the presence of impurities.