ONE-DIMENSIONAL RANDOM FIELD ISING-MODEL - RESIDUAL ENTROPY, MAGNETIZATION, AND THE PERESTROIKA OF THE GROUND-STATE

The discontinuous behaviour of magnetization and entropy for zero temperature can be understood as the consequence of flips of microscopic spin clusters. The residual entropy feels very sensitively whether the ration of constant and random part of the magnetic field is rational or irrational, since in the former case an additional mechanism for degeneracy of the ground state appears. © 1990.