Elastic broadening of quasiparticle energy levels in vortex cores of high-T c superconductors

The influence of elastic scatterers, both short ranged as well as long ranged, on the density of quasiparticle energy states in the vortex cores of high-Tc superconductors is calculated. For short-range scatterers, the reduction of the density at energy values corresponding to the clean system's energy levels is exactly calculated by diagram summation. An expression for the broadening of the density of states (DOS) as a function of disorder is given. For long-range scatterers, the DOS as a function of the probability distribution of the scatterers is also calculated. In both cases a similar broadening of the DOS peaks is predicted. This might be useful in explaining experiments probing the density of states of vortex excitations.