Hysteresis loop signatures of phase transitions in a mean-field model of disordered Ising magnet
P. N. Timonin
Southern Federal University, 344090 Rostov-on-Don, Russia
Abstract
The multiplicity of long-lived states in frustrated disordered
magnets makes the task to experimentally determine which of them has the
lowest free energy (and thus what thermodynamic phase the sample is in) seem
rather hopeless. Nevertheless here we show in the framework of Landau-type
phenomenological model that signatures of the mean-field equilibrium phase
transitions in such highly nonequilibrium systems may be found in the
evolution of the hysteresis loop form. Thus the sequence of transitions from
spin-glass to mixed phase and to ferromagnetic one results in the changes
from inclined hysteresis loop to that with the developing vertical sides and
to one with the perfectly vertical sides. Such relation between loop form and
the location of global minimum may hold beyond the mean-field approximation
and can be useful in the real experiments and Monte-Carlo simulations of the
problems involving rugged potential landscape.