Local density of states and Friedel oscillations around a nonmagnetic impurity in unconventional density waves

摘要

We present a mean-field theoretical study on the effect of a single nonmagnetic impurity in quasi-one-dimensional unconventional density wave. The scattering potential is treated within the self-consistent T-matrix approximation. The local density of states around the impurity exhibits resonant states in the vicinity of the Fermi level, much the same way as in d density waves or unconventional superconductors. The assumption for different forward and backward scattering, characteristic to quasi-one-dimensional systems in general, leads to a resonance state that is double peaked in the pseudogap. The Friedel oscillations around the impurity are also explored, both within and beyond the density wave coherence length ξ_0. Beyond ξ_0, we find power-law behavior as opposed to the exponential decay of conventional density wave.