Related papers: Aging and Memory Effects in Superparamagnets and S…
Aging phenomena of short-range Ising spin glass models have been investigated using Monte Carlo simulations. It is found that in the low-temperature spin-glass phase the mean domain size exhibits a crossover from a power-law growth…
The relaxation dynamics of many disordered systems, such as structural glasses, proteins, granular materials or spin glasses, is not completely frozen even at very low temperatures. This residual motion leads to a change of the properties…
Iron, cobalt and nickel nanoparticles, grown in the gas phase, are known to arrange in chains and bracelet-like rings due to the long-range dipolar interaction between the ferromagnetic (or super-paramagnetic) particles. We investigate the…
The relaxor ferroelectric (PbMn$_{1/3}$Nb$_{2/3}$O$_3$)$_{1-x}$(PbTiO$_3$)$_{x}$, $x=0.1$, (PMN/PT(90/10)) is found to exhibit several regimes of complicated aging behavior. Just below the susceptibility peak there is a regime exhibiting…
We have examined the nonconventional spin glass phase of the 2-dimensional kagome antiferromagnet (H_3 O) Fe_3 (SO_4)_2 (OH)_6 by means of ac and dc magnetic measurements. The frequency dependence of the ac susceptibility peak is…
We present a detailed study of simple `tree' models for off equilibrium dynamics and aging in glassy systems. The simplest tree describes the landscape of a random energy model, whereas multifurcating trees occur in the solution of the…
We introduce an efficient dynamical tree method that enables us, for the first time, to explicitly demonstrate thermo-remanent magnetization memory effect in a hierarchical energy landscape. Our simulation nicely reproduces the nontrivial…
Dynamic magnetic properties and ageing phenomena of the re-entrant ferromagnet (Fe0.20Ni0.80)75P16B6Al3 are investigated by time dependent zero field cooled magnetic relaxation, m (t), measurements. The influence of a temperature cycling…
In the past several years, many important innovations in nanotechnology were made. Today it becomes possible to make nanosize magnetic particles, and development of high storage-density magnetic device is desired. In such a magnetic…
We have performed a series of measurements on the low temperature behavior of a magnetic nano-particle system. Our results show striking memory effects in the dc magnetization. Dipolar interactions among the nano-particles {\em suppress}…
We show results of simulations of a weakly driven four dimensional Edwards- Anderson spin glass, which presents clear signatures of dynamical ultrametricity at low temperatures. The presence of a hierarchical organization of time scales is…
Detailed dc and ac magnetic properties of chemically synthesized Nd0.4Sr0.6MnO3 with different particle size (down to 27 nm) have been studied in details. We have found ferromagnetic state in the nanoparticles, whereas, the bulk…
Using a nonequilibrium Monte Carlo method suitable to nanomagnetism, we investigate representative systems of interacting sub-10nm grained nanomagnets with large uniaxial anisotropy. Various magnetization memory and aging effects are found…
Recent work has suggested the existence of glassy behavior in a ferromagnetic model with a four-spin interaction. Motivated by these findings, we have studied the dynamics of this model using Monte Carlo simulations with particular…
Crystalline Mn5Ge3 nanomagnets are formed inside a Mn-diluted Ge matrix using Mn ion implantation. A temperature-dependent memory effect and slow magnetic relaxation are observed below the superparamagnetic blocking temperature of Mn5Ge3.…
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…
We summarize the different puzzles raised by aging experiments of spin-glasses and their various interpretations. We try to reconcile the `real space', droplet like pictures with the hierarchical pictures that have been proposed in the…
Aging is a well known property of spin glass materials and has been investigated extensively in recent years. This aging effect is commonly observed by thermal remnant magnetization (TRM) experiments in which the relaxation of the…
The low temperature dynamics of the three dimensional Ising spin glass in zero field with a discrete bond distribution is investigated via MC simulations. The thermoremanent magnetization is found to decay algebraically and the temperature…
The low temperature dynamics of the three dimensional Ising spin glass in zero field with a discrete bond distribution is investigated via MC simulations. The thermoremanent magnetization is found to decay algebraically and the temperature…