Memory effects in Heisenberg spin glasses: Spontaneous restoration of the original spin configuration rather than preservation in a frozen state

Abstract

Universality of spin configuration restoration is studied in Heisenberg spin glasses: a dilute magnetic semiconductor Cd55Mn45Te as well as a dilute magnetic alloy Cu97Mn3. Reversions of the relaxations of magnetization were observed in both systems undergoing positive/negative temperature cycling under a constant magnetic field. Because the magnetization mirrors evolution of the spin configuration, these reversions indicate that the spin configurations are spontaneously restored to the initially stabilized states when the temperature is returned to the original. Whereas such spin restoration does not occur if the spin glasses are simply frozen, it is possible in the alternative ghost domain scenario of the droplet picture. This finding thus provides fresh insight into the nature of glassy systems.