Calculation of the order-parameter relaxation times in superconducting aluminum

Abstract The principal dielectric permittivity components in the nematic phase of 4-rc-hexyloxy-4’-cyanobiph-enyl (60CB) were measured as functions of temperature at ambient pressure and as functions of pres-sure up to 100 MPa at several constant temperatures. The dielectric anisotropy is analized in the frame of the Maier-Meier equations. The pressure dependence of the order parameter is deduced. Preliminary results for the activation volume and activation enthalpy from the pressure and temperature dependenc-es of the longitudinal relaxation times are obtained.

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On the derivation of the nematic order parameter from the dielectric relaxation times

Physical Chemistry Chemical Physics ◽

10.1039/a901368g ◽

1999 ◽

Vol 1 (11) ◽

pp. 2787-2791 ◽

Cited By ~ 30

Author(s):

Stanisław Urban ◽

Albert Würflinger ◽

Bo Gestblom

Keyword(s):

Dielectric Relaxation ◽

Order Parameter ◽

Relaxation Times ◽

Nematic Order

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Frequency Variation of the AC Order Parameter Susceptibility of the Metamagnetic Ising Model

Advances in Condensed Matter Physics ◽

10.1155/2018/8479684 ◽

2018 ◽

Vol 2018 ◽

pp. 1-12

Author(s):

Gul Gulpinar

Keyword(s):

Order Parameter ◽

Relaxation Times ◽

Rate Coefficients ◽

Irreversible Processes ◽

Frequency Variation ◽

Iron Group ◽

Extensive Investigation ◽

Field Frequency ◽

Step Process ◽

Onsager Theory

The extensive investigation of the absorptive and reactive parts of the AC order parameter susceptibility spectra of iron group dihalides, which is obtained on the basis of Onsager theory of irreversible processes, revealed the fact that the diagonal phenomenological rate coefficients γs and γm have an important impact on the nature of the order parameter relaxation process. The number of the relaxation peaks appearing in the double logarithmic plots of χs′′ versus field frequency ω and the number of plateau regions in χs′ spectrum depends on the values of γs and γm. Only for γs≫γm does the relaxation evolve from a simple Debye exponential at high temperatures to a two-step process at lower temperatures in which there exist two long relaxation times characterizing the relaxation of staggered magnetization. In parallel with these characteristics of the order parameter relaxation, Cole-Cole plots (χs′′-χs′) are shown to consist of two arcs in the metamagnetic phase and of a semicircle in the paramagnetic phase.

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PHASE TRANSITIONS IN THE COLLECTIVE MOTION OF SELF-PROPELLED INDIVIDUALS

International Journal of Modern Physics C ◽

10.1142/s0129183106008492 ◽

2006 ◽

Vol 17 (03) ◽

pp. 395-402 ◽

Cited By ~ 3

Author(s):

GABRIEL BAGLIETTO ◽

EZEQUIEL V. ALBANO

Keyword(s):

Phase Transitions ◽

Time Dependence ◽

Relaxation Process ◽

Computer Simulations ◽

Order Parameter ◽

Collective Motion ◽

Relaxation Times ◽

Low Noise ◽

Noise Levels ◽

First Order

A model for the displacement of self-driven organisms is studied by means of extensive computer simulations. Local interactions influenced by noisy communications among organisms, leads to the onset of collective motion at low noise levels. When the noise is increased the system undergoes first-order transitions into disordered states of motion. We have also studied the relaxation process between these states. By fitting the time dependence of the order parameter when the system is annealed from a state below coexistence to another above it, we conclude that the relaxation can be well described by means of a stretched exponential. In this way the characteristic relaxation times are obtained.

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Order-Parameter Relaxation Times of Finite Three-Dimensional Ising-like Systems

Physical Review Letters ◽

10.1103/physrevlett.77.1789 ◽

1996 ◽

Vol 77 (9) ◽

pp. 1789-1792 ◽

Cited By ~ 25

Author(s):

W. Koch ◽

V. Dohm ◽

D. Stauffer

Keyword(s):

Order Parameter ◽

Relaxation Times ◽

Three Dimensional

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An emerging technology: Nuclear magnetic resonance microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010010706x ◽

1988 ◽

Vol 46 ◽

pp. 1000-1001

Author(s):

M.J. Hennessy ◽

E. Kwok

Keyword(s):

Nuclear Magnetic Resonance ◽

Magnetic Resonance ◽

Relaxation Times ◽

Basic Research ◽

Local Environment ◽

Magnetic Resonance Images ◽

Nmr Microscopy ◽

Mri Scans ◽

Temperature Relaxation ◽

Nuclear Magnetic

Much progress in nuclear magnetic resonance microscope has been made in the last few years as a result of improved instrumentation and techniques being made available through basic research in magnetic resonance imaging (MRI) technologies for medicine. Nuclear magnetic resonance (NMR) was first observed in the hydrogen nucleus in water by Bloch, Purcell and Pound over 40 years ago. Today, in medicine, virtually all commercial MRI scans are made of water bound in tissue. This is also true for NMR microscopy, which has focussed mainly on biological applications. The reason water is the favored molecule for NMR is because water is,the most abundant molecule in biology. It is also the most NMR sensitive having the largest nuclear magnetic moment and having reasonable room temperature relaxation times (from 10 ms to 3 sec). The contrast seen in magnetic resonance images is due mostly to distribution of water relaxation times in sample which are extremely sensitive to the local environment.

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