Related papers: Numerical exploration of the Aging effects in spin…
The earlier times of evolution of a magnetic system contain more information than we can imagine. Capturing correlation matrices G of different time evolutions of a simple testbed spin system, as the Ising model, we analyzed the density of…
Our research highlights the effectiveness of utilizing matrices akin to Wishart matrices, derived from magnetization time series data under specific dynamics, to elucidate phase transitions and critical phenomena in the Q-state Potts model.…
The dynamic effects on a magnetic system exposed to a time-oscillating external temperature are studied using Monte Carlo simulations on the classic 2D Ising Model. The time dependence of temperature is defined as $T(t)=T_0 + A \cdot…
Recent studies on the phenomenology of ageing in certain many-particle systems which are at a critical point of their non-equilibrium steady-states, are reviewed. Examples include the contact process, the parity-conserving…
Starting from the canonical ensemble over the space of pure quantum states, we obtain an integral representation for the partition function. This is used to calculate the magnetisation of a system of N spin-1/2 particles. The results…
The discovery of memory effects in the magnetization decays of spin glasses in 1983 began a large effort to determine the exact nature of the decay. While qualitative arguments have suggested that the decay functions should scale as…
We use Monte-Carlo simulations to study aging phenomena and the occurence of spinglass phases in systems of single-domain ferromagnetic nanoparticles under the combined influence of dipolar interaction and anisotropy energy, for different…
Spin dimer systems are a promising playground for the detailed study of quantum phase transitions. Using the magnetic field as the tuning parameter it is in principle possible to observe a crossover from the characteristic scaling near…
The deviations from full or pure aging behavior, i.e. perfect $t/t_w$ scaling of the correlation and response functions of aging glassy systems, are not well understood theoretically. Recent experiments of Rodriguez et al. (Phys. Rev. Lett.…
We study the effect of temperature shift on aging phenomena in the Random Energy Model (REM). From calculation on the correlation function and simulation on the Zero-Field-Cooled magnetization, we find that the REM satisfies a scaling…
The long-time dynamics of the critical contact process which is brought suddenly out of an uncorrelated initial state undergoes ageing in close analogy with quenched magnetic systems. In particular, we show through Monte Carlo simulations…
Magnetizations are introduced to the Generalized Random Energy Model (GREM) and numerical simulations on ac susceptibility is made for direct comparison with experiments in glassy materials. Prominent dynamical natures of spin glasses, {\it…
We present the first experimental determination of the time autocorrelation $C(t',t)$ of magnetization in the non-stationary regime of a spin glass. Quantitative comparison with the response, the magnetic susceptibility $\chi(t',t)$, is…
Different aspects of critical behaviour of magnetic materials are presented and discussed. The scaling ideas are shown to arise in the context of purely magnetic properties as well as in that of thermal properties as demonstrated by…
In this set of five lectures the authors have presented techniques to analyze open classical and quantum systems using correlation matrices. For diverse reasons we shall see that random matrices play an important role to describe a null…
These lecture notes introduce quantum spin systems and several computational methods for studying their ground-state and finite-temperature properties. Symmetry-breaking and critical phenomena are first discussed in the simpler setting of…
The temperature dependence of the magnetisation of a Cu(Mn) spin glass ($T_g$ $\approx$ 57 K) has been investigated using weak probing magnetic fields ($H$ = 0.5 or 0 Oe) and specific thermal protocols. The behaviour of the zero-field…
The short-time behaviour of the critical dynamics for magnetic systems is investigated with Monte Carlo methods. Without losing the generality, we consider the relaxation process for the two dimensional Ising and Potts model starting from…
Currently, aging effects occurring in multilayer systems attract much attention from researchers. In our research we looked at the behavior of multilayer systems that depend on anisotropy, magnetoresistance and susceptibility.All these…
The kinetics of the long-range spherical model evolving from various initial states is studied. In particular, the large-time auto-correlation and -response functions are obtained, for classes of long-range correlated initial states, and…