Disorder-enhanced electron correlations near the crystalline-amorphous transition

The static density response chi(0, q) of a disordered electron sea in the presence of Coulomb interaction is calculated for a situation where diffusive relaxation dominates other decay processes. It is argued that this condition is realized near the crystalline-amorphous transition of certain binary alloys. Below a critical temperature, chi(0, q) exhibits a powerlaw divergence at the Fermi surface (q = 2k(F)). It causes a systematical phase shift of the Friedel oscillations as well as an enhancement of their amplitude. The spatial decay exponent of the Friedel oscillations is also modified. Our results are consistent with experiments and are relevant for understanding the stability of the amorphous state against crystallization.