EFFECT OF MAGNETIC-FIELDS ON THE RELAXATION OF THE THERMOREMANENT MAGNETIZATION IN SPIN-GLASSES

We have measured the magnetic field dependence of the low-field thermo remanent magnetization decays for both long and short waiting times co mpared with the observation times in a Cu-Mn spin glass. By introducin g an energy phase space which is composed of metastable states separat ed by increasing energy barriers as a function of their Hamming distan ce, the quenching of the magnetic field corresponds to a Zeeman 'tilti ng' of the phase space towards states with zero magnetization. This qu alitative picture is consistent with our experimental observations.