Superconductivity suppression in (Er1-xPrx)Ba2Cu4O8: an x-ray absorption spectroscopic study

In this letter we report our measurements of Er and Pr L-3 edges in Er1-xPr xBa2Cu4O8, 0 less than or equal to x less than or equal to 0.6. The normali zed L-3-edge intensity is seen to closely follow the behaviour of T-c with the Pr concentration in these compounds. This can be related to the fact th at there is a reduction in the number of mobile carriers with increasing Pr -doping level. This picture lends support to a recent model proposed by Lie chtenstein and Mazin (Liechtenstein A I and Mazin I I 1995 Phys. Rev. Lett. 70 1000) according to which the holes are localized in a band which crosse s the Fermi level along with a hybridized state of 4f(2)L and 4f(1) at the Pr site, where L is a ligand hole.