The 3d Ising spin glass

Nordblad, Per

doi:10.1590/s0103-97332000000400024

Cited by 3 publications

(4 citation statements)

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“…This cusp is the unique characteristic signature of either superparamagnetic or spin-glass states; however, the samples lacked the irreversibility of the field-cooled (FC) curve, or thermoremnant (TRM) magnetization, which is characteristic of a spin-glass state. 19 Furthermore, the maximum blocking temperature, T B,max , 20 or the temperature where initial bifurcation between the ZFC and FC curves occurs, decreases with purification from r-SWNTs to US-tubes (Figure 3). This indicates that as T B,max approaches T B , the net distribution of superparamagnetic domain sizes becomes more uniform.…”

Section: Resultsmentioning

confidence: 98%

“…The r-SWNTs (Figure a), p-SWNTs (Figure b), and US-tubes (Figure c) data are all consistent with superparamagnetism; the zero-field-cooled (ZFC) curves are characterized by a mean blocking temperature, T B , above which the material is superparamagnetic and below which magnetic viscosity gives rise to a hysteretic magnetization loop. This cusp is the unique characteristic signature of either superparamagnetic or spin-glass states; however, the samples lacked the irreversibility of the field-cooled (FC) curve, or thermoremnant (TRM) magnetization, which is characteristic of a spin-glass state . Furthermore, the maximum blocking temperature, T B,max , or the temperature where initial bifurcation between the ZFC and FC curves occurs, decreases with purification from r-SWNTs to US-tubes (Figure ).…”

Section: Resultsmentioning

confidence: 99%

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Single-Walled Carbon Nanotube Materials as T₂-Weighted MRI Contrast Agents

et al. 2009

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With their unique nanoscalar properties, single-walled carbon nanotube (SWNT) materials are widely studied for various biological applications. Herein, we report the efficiency of full-length HiPco SWNTs and ultra-short SWNTs (US-tubes) as T 2-weighted MRI contrast agents. Analysis has concluded that the superparamagnetic SWNT materials (especially US-tubes) are a new class of high-efficacy contrast agents having performance contributions from both the iron catalyst nanoparticles (originating from the synthesis of SWNT materials) and the carbon SWNT material itself. The superparamagnetic US-tubes with their short length (<100 nm), negligible metal content (<1% Fe (wt %)), and superior T 2 relaxation efficiency (T 2 = 31.7 ms per mg SWNT at 3 T and 37 °C) are the most promising candidates for advanced applications such as molecular and cellular imaging using MRI.

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Section: Resultsmentioning

confidence: 98%

Section: Resultsmentioning

confidence: 99%

Single-Walled Carbon Nanotube Materials as T₂-Weighted MRI Contrast Agents

et al. 2009

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“…Analyses of these results in terms of Eq. 1 yield zν = 10±0.5 [5] which can be used as a reference value for the dynamic exponent of three-dimensional Ising spin-glasses [6].…”

Section: Glassy Dynamics -Aging -Magnetic Model Systemsmentioning

confidence: 99%

“…Figure 3 shows the in and out-of-phase component of the low field ac-susceptibility of Fe 0.5 Mn 0.5 TiO 3 over a wide frequency range near the spin-glass transition. Analyses of these results in terms of equation ( 1) yield zν = 10 ± 0.5 [4] which can be used as a reference value for the dynamic exponent of three-dimensional Ising spin-glasses [5].…”

Section: Glassy Dynamics-ageing-magnetic Model Systemsmentioning

confidence: 99%

Competing interaction in magnets: the root of ordered disorder or only frustration?

Nordblad¹

2013

Phys. Scr.

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What does the equilibrium atomic, molecular or spin configuration of a glass phase look like? Is there only one unique equilibrium configuration or are there infinitely many configurations of equal energy? The processes and mechanisms governing the path towards equilibrium, i.e. the dynamics of glassy systems, provide insights to these questions. Here we discuss the intrinsic dynamics of different glassy magnets: of spin-glasses, frustrated ferromagnets, superspin-glasses and other nanostructured systems with competing ferro-and antiferromagnetic interactions and randomness in their spatial distribution. This paper is intended as a brief update on some unsolved problems and the current empirical status in the field of disordered and frustrated magnetism. IntroductionTemperature (thermal energy) favours disordered states of matter. Interatomic forces strive to condense matter to states of perfect order. Randomness and defects -quenched disorder necessarily accompany the atomic structural order of crystalline matter. Magnetic materials mirror and illustrate consequences of these counteracting influences. Strong direct exchange interaction between the atoms in iron causes ferromagnetic order well above room temperature. The degree of atomic disorder in the crystal structure governs the magnetic functionality of iron-based alloys -allowing soft (transformer sheet) or hard (permanent magnet) magnetic behaviour.

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