Low-energy density of states for disordered magnetic chains

Abstract

We extend earlier calculations of the low-energy density of states of a disordered magnetic chain to a third and intermediate class of random nearest-neighbor exchange interactions. In this intermediate class the probability of a zero-exchange interaction tends to a nonzero constant. We calculate the density of states for systems belonging to this intermediate class using the coherent-potential approximation and compare the results with those of exact numerical calculations on finite arrays. The existence of a logarithmic correction predicted earlier is established.