Localization phenomena in the random XXZ spin chain

Abstract: It is shown that the infinite random Heisenberg XXZ spin-$\frac12$ chain exhibits, with probability one, spectral, eigenstate, and weak dynamical localization in an arbitrary (but fixed) energy interval in a non-trivial parameters range. The crucial step in the argument is a proof that if the Green functions for the associated finite systems Hamiltonians exhibit certain (volume-dependent) decay properties in a fixed energy interval, then the infinite volume Green function decays in the same interval as well. The pertinent finite systems decay properties for the random XXZ model had been previously verified by the authors.