Speaker
Description
In experimental studies of aging, the temperature T is externally controlled and
identified as the phonon “bath” temperature measured on a thermometer.
Aging is a non-linear phenomenon. Thus the response of the system to a small
perturbation is not linear and it depends on both sign and magnitude of input.
For instance, consider small up temperature and down temperature jump to the
same temperature (symmetry up and down jump). The two responses will not
be mirror symmetric, the down jump will appear quite flat and reaching
equilibrium much faster than the up jump. The up jump – while slower in the
beginning – will show steeper approach to equilibrium. This is so called fictive
temperature effect, an effect which comes from the fact that the relaxation rate is structure dependent and itself evolve with time. Our main purpose of this
study is to investigate the controlling parameter behind this effect in simulation
as previously confirmed in experiments.
The TN-formalism interprets aging in terms of a material time, ξ. The material
time maybe thought of as a time measured on a clock with a clock rate that
changes as the system ages. The material time define from the clock rate γ(t) by
dξ=γ(t)dt. Suppose a single parameter that controls both clock rate and
measured quantity. The physical nature of this single parameter is irrelevant. If
single parameter aging obeyed, it is possible to predict one jump from the
relaxation function of another jump. Single parameter aging tests were derived
by Hecksher et al.2015 for jumps that ending same temperature. Lisa et al.2018
tested single parameter aging either for ending to same temperature or to
different temperature. Our main purpose is to study validity of single parameter
aging theory by computer simulation.
