Memory and superposition in a spin glass

Mathieu, Roland; Jönsson, Petra E.; Nam, D. N. H.; Nordblad, Per

doi:10.1103/physrevb.63.092401

Cited by 158 publications

(168 citation statements)

References 11 publications

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“…These experiments showed not only rejuvenation effects but also that spin glass order, characteristic of different temperatures, can coexist on different length scales; hence the spin glass keeps a memory of its thermal history. A simple experimental protocol [85] was employed to illustrate memory and rejuvenation effects [110][111][112][113]; the sample is cooled from a high temperature with one (or more) halts of the cooling at one (or more) temperatures in the spin glass phase. The experimental procedure of a double-stop experiment is illustrated in Fig.…”

Section: Experiments: Aging Memory and Rejuvenationmentioning

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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Section: Experiments: Aging Memory and Rejuvenationmentioning

confidence: 99%

Superparamagnetism and Spin Glass Dynamics of Interacting Magnetic Nanoparticle Systems

Jönsson

2003

Advances in Chemical Physics

124

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“…[5][6][7][8][9] Very recently, Sun et al performed a series of measurements on an interacting particle system and observed striking memory effects in the dc magnetization and magnetic relaxation. 12 It has been suggested that the striking memory effects go beyond those previously observed in standard experiments and should be associated with a hierarchical model rather than a droplet model.…”

Section: Introductionmentioning

confidence: 99%

“…[2][3][4][5][6] Different experimental approaches have been employed to observe the memory effect in spin-glass system and particle systems. [2][3][4][5][6][7][8][9][10] The most acceptable experimental approaches for observing the memory effect include low frequency ac susceptibility 2-8 ͑ = Ј+ Љ͒ and low field dc magnetization measurements. 5,6,9,10 The experimental details for each approach are briefly described as the following.…”

Section: Introductionmentioning

confidence: 99%

Memory effects in a nanoparticle system: Low-field magnetization and ac susceptibility measurements

Zheng

et al. 2005

Phys. Rev. B

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A dilute magnetic liquid with Co nanoparticles with an average diameter of 5 nm in hexane has been studied systematically following the experimental approach proposed recently for observing memory effects in magnetic nanoparticles. All phenomena reported previously have been observed, which were earlier ascribed to the memory effect. However, the standard experiments for observing memory effects ͑low frequency as susceptibility and low field dc magnetization measurements͒ do not show the memory effect. To understand those observations, very detailed physical pictures, based on the relaxation of the individual particle, are proposed here.

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“…1(b)] indicating absence of spin glass order. In addition, another typical signature of spin glass relaxation, ''memory effect'' [23], was not observed in this material.…”

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confidence: 91%

“…Such relaxation can be even extended for a cooperative system like a spin glass with an additional input t w due to memory of historical events of the system [24]. One can readily test this fundamental signature by the principle of superposition, as follows [23,24]:…”

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confidence: 99%

Magnetic Bistability and Nucleation of Magnetic Bubbles in a Layered 2D Organic-Based Magnet[Fe(TCNE)(NCMe)2][

et al. 2008

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The 2D layered organic-based magnet ½FeðTCNEÞðNCMeÞ 2 ½FeCl 4 (TCNE ¼ tetracyanoethylene) exhibits a unique macroscopic magnetic bistability between the field-cooled and zero-field-cooled states, which cannot be explained by either superparamagnetic behavior or spin freezing due to spin glass order. This magnetic bistability is described through consideration of the ensemble of uncoupled 2D Ising layers and their magnetization reversal initiated by a field-induced nucleation of magnetic bubbles in individual layers. The bubble nucleation rate strongly depends on the external field and temperature resulting in anomalous magnetic relaxation. DOI: 10.1103/PhysRevLett.101.197206 PACS numbers: 75.50.Xx, 75.60.Jk, 75.70.Ak, 75.70.Kw Recent years have witnessed growing attention to organic-based magnets due to their new phenomena and opportunities [1]. The magnetic properties of these materials can be tuned to meet the applications, creating ''magnets by design'' [2,3]. This opens a variety of possibilities for developing materials with the desired magnetic properties, such as magnetic coupling, dimensionality, type of spin, anisotropy, coercivity, etc. One of the interesting phenomena in this class of magnets is ''magnetic bistability.'' Notable examples are spin-crossover complexes, which exhibit thermal transition between high-spin and low-spin states [4], high-spin complexes, which demonstrate macroscopic quantum tunneling of magnetization [5,6] and mixed ferro-ferrimagnetic Prussian blue analogs, which display multiple compensation temperatures [7]. In addition, their magnetic bistabilities often can be controlled by the optical excitation [8][9][10][11][12][13].In this Letter, we report unique properties of magnetic bistability of the 2D layered system ½FeðTCNEÞ-ðNCMeÞ 2 ½FeCl 4 (TCNE ¼ tetracyanoethylene) [14]. The dc magnetization displays anomalous irreversibility between zero-field-cooled (ZFC) and field-cooled (FC) states, which we propose to originate from magnetization reversal of single 2D layers through the nucleation and growth of ''bubble domains.'' We show that the rate of bubble generation together with the bubble size and characteristic relaxation time are strongly contingent on the external magnetic field (H) and thermal energy (k B T).Metal-TCNE magnets are a class of organic-based magnets that have been extensively studied. They form a variety of structures ranging from 1-D chain to 3-D network structures, which even show room temperature magnetic ordering for some compositions [15][16][17][18]. For example, the VðTCNEÞx, x $ 2 has a magnetic ordering temperature (T c ) $400 K with highly spin-polarized valence and conduction bands [15,16,19]. Recently, the first crystal structure of a metal-TCNE magnet, ½FeðTCNEÞ-ðNCMeÞ 2 ½FeCl 4 , was reported [14]. The structure consists of undulating layers composed of Fe II ions with a 4 -½TCNE ÁÀ bridging within the layer and two axial MeCNs coordinations [14]. There are no covalent bonds between layers [14]. Additional paramagnetic ½FeCl 4 À anions occ...

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Memory and superposition in a spin glass

Cited by 158 publications

References 11 publications

Superparamagnetism and Spin Glass Dynamics of Interacting Magnetic Nanoparticle Systems

Superparamagnetism and Spin Glass Dynamics of Interacting Magnetic Nanoparticle Systems

Memory effects in a nanoparticle system: Low-field magnetization and ac susceptibility measurements

Magnetic Bistability and Nucleation of Magnetic Bubbles in a Layered 2D Organic-Based Magnet[Fe(TCNE)(NCMe)2][

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