Aging and memory effects in a disordered crystal

Doussineau, P.; Lacerda-Arôso, T. de; Levelut, A.

doi:10.1209/epl/i1999-00275-y

Cited by 48 publications

(66 citation statements)

References 18 publications

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“…At all temperatures T i (hence in both phases), we find that when cooling is resumed after aging χ ′′ merges back (even increasing in some cases) with the reference curve, although this reference is a non-equilibrium curve. This happens here exactly like in spin glasses [1,4,5,6], in a similar fashion as in some other systems [12,13]. Aging processes have to restart at lower temperatures, as if the aging evolution was not cumulative with that at a higher temperature ('chaos-like' or 'rejuvenation' effect), in contrast with the continuous hysteresis phenomenon displayed in Fig.2.…”

supporting

confidence: 71%

Aging phenomena in spin-glass and ferromagnetic phases: Domain growth and wall dynamics

Vincent¹,

Dupuis²,

Alba³

et al. 2000

Europhys. Lett.

113

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PACS. 02.75.50.Lk -Spin glasses and other random magnets. PACS. 03.75.10.Nr -Spin-glass and other random models. PACS. 04.75.40.Gb -Dynamic properties (dynamic susceptibility, spin waves, spin diffusion, dynamic scaling, etc.).Abstract. -We compare aging in a disordered ferromagnet and in a spin glass, by studying the different phases of a reentrant system. We have measured the relaxation of the low-frequency ac susceptibility χ, in both the ferromagnetic and spin-glass phases of a CdCr1.9In0.1S4 sample. A restart of aging processes when the temperature is lowered ('chaos-like' effect) is observed in both phases. The memory of previous aging at a higher temperature can be retrieved upon re-heating, but in the ferromagnetic phase it can rapidly be erased by the growth of ferromagnetic domains. We interpret the behaviour observed in the ferromagnetic phase in terms of a combination of domain growth and pinned wall reconformations, and suggest that aging in spin glasses is dominated by such wall reconformation processes.

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supporting

confidence: 71%

Aging phenomena in spin-glass and ferromagnetic phases: Domain growth and wall dynamics

Vincent¹,

Dupuis²,

Alba³

et al. 2000

Europhys. Lett.

113

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“…The difference between the observed value in the cooling and that in the reheating is not observed in spin glasses, while the hysteresis is observed in other glassy materials, such as polymer glasses, 21) orientational glasses 22) and disordered ferromagnets. 23) In the second run, the sample is cooled from T max to a waiting temperature T wait (T min < T wait < T c ), and is kept at T wait during a certain time interval.…”

Section: §1 Introductionmentioning

confidence: 72%

“…In this dynamics, the time evolution in the vicinity of T c is very important. Polymers, 21, 26) supercooled glycerol 27) and the orientational glasses 22,28) belong to this type. Now let us discuss how these two distinct types of dynamics observed in glassy materials are interpreted within the GREM.…”

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confidence: 99%

Numerical Study of Aging in the Generalized Random Energy Model

Sasaki

Nemoto

2001

J. Phys. Soc. Jpn.

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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, i.e., memory effect and reinitialization, are reproduced well in the GREM. The existence of many layers causing continuous transitions is very important for the two natures. Results of experiments in other glassy materials such as polymers, supercooled glycerol and orientational glasses, which are contrast to those in spin glasses, are interpreted well by the Single-layer Random Energy Model.KEYWORDS: aging, generalized random energy model, memory effect, reinitialization, temperature specific dynamics, cumulative dynamics §1. IntroductionIn spin glasses, it is well known that dynamical behavior strongly depends on history of the system after quenching from above the transition temperature T c . These phenomena are called aging and have been studied with various experimental protocols such as the isothermal, 1, 2) the T -shift 3, 4) and the T -cycle one. 5,6,7,8,9) From the theoretical point of view, aging phenomena have been studied along two different pictures, i.e., so-called droplet picture 10,11,12,13) and hierarchical picture. 5,7,8) The Generalized Random Energy Model (GREM) 14,15,16,17) is a model that belongs to the latter. This model has a hierarchical structure causing continuous transitions as the system is cooled down. These continuous transitions correspond to successive branching process of free energy in the hierarchical picture. Bouchaud and Dean 14) have shown that aging naturally occurs in this model and the time correlation function C(t + t w , t w ) satisfies a t/t w scaling law. Furthermore, we have recently made simulations 18,19) similar to experiments on aging phenomena with temperature variations. As the consequence, it has been shown that results of experiments are reproduced well according to the hierarchical picture.Recently, Jonason et al 20) have made a new experiment, in which curious dynamical natures of spin glasses are observed very clearly. This experiment consists of the following two runs. In the first run, the sample is continuously cooled from T max (> T c ) to T min (< T c ) at a constant rate, 1 and is immediately reheated at the same rate. During the cooling and the reheating, out-of-phase ac-susceptibility χ ′′ is measured as a function of temperature. We call this curve as χ ′′ ref .The difference between the observed value in the cooling and that in the reheating is not observed in spin glasses, while the hysteresis is observed in other glassy materials, such as polymer glasses, 21) orientational glasses 22) and disordered ferromagnets. 23) In the second run, the sample is cooled from T max to a waiting temperature T wait (T min < T wait < T c ), and is kept at T wait during a certain time interval. The sample ages and χ ′′ decreases during the interval. Then the system is cooled to T min and is reheated to T max without any stops. Her...

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“…It can be seen that the relaxation rate S(t) = h −1 dM/d log t exhibits a maximum at t ∼ t w [89,90]. Many different types of materials were later shown to exhibit aging and nonequilibrium dynamics, including polymers [91], orientational glasses [92], gels [93], and ceramic superconductors [94]. Spin glass systems represent ideal model systems for studying nonequilibrium dynamics experimentally, numerically, and theoretically.…”

Section: Nonequilibrium Dynamicsmentioning

confidence: 99%

Superparamagnetism and Spin Glass Dynamics of Interacting Magnetic Nanoparticle Systems

Jönsson

2003

Advances in Chemical Physics

124

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Jönsson, P. 2002. Anisotropy, disorder and frustration in magnetic nanoparticle systems and spin glasses. Acta Universitatis Upsaliensis. Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 727. 71 pp. Uppsala. ISBN 91-554-5344-9.Magnetic properties of nanoparticle systems and spin glasses have been investigated theoretically, and experimentally by squid magnetometry.Two model three-dimensional spin glasses have been studied: a long-range Ag(11 at% Mn) Heisenberg spin glass and a short-range Fe0.5Mn0.5TiO3 Ising spin glass. Experimental protocols revealing ageing, memory and rejuvenation phenomena are used. Quantitative analyses of the glassy dynamics within the droplet model give evidences of significantly different exponents describing the nonequilibrium dynamics of the two samples. In particular, non-accumulative ageing related to temperaturechaos is much stronger in Ag(11 at% Mn) than in Fe0.5Mn0.5TiO3.

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Aging and memory effects in a disordered crystal

Cited by 48 publications

References 18 publications

Aging phenomena in spin-glass and ferromagnetic phases: Domain growth and wall dynamics

Aging phenomena in spin-glass and ferromagnetic phases: Domain growth and wall dynamics

Numerical Study of Aging in the Generalized Random Energy Model

Superparamagnetism and Spin Glass Dynamics of Interacting Magnetic Nanoparticle Systems

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