Gilbert ferromagnetic damping theory and the fluctuation-dissipation theorem

2010 ◽  
Vol 108 (7) ◽  
pp. 073924 ◽  
Author(s):  
A. Widom ◽  
C. Vittoria ◽  
S. D. Yoon
Keyword(s):  
Fluctuation Dissipation ◽  
Fluctuation Dissipation Theorem ◽  
Damping Theory

scholarly journals The Response to Stratospheric Forcing and Its Dependence on the State of the Troposphere

2009 ◽  
Vol 66 (7) ◽  
pp. 2107-2115 ◽  
Author(s):  
Cegeon J. Chan ◽  
R. Alan Plumb
Keyword(s):  
Time Scale ◽  
Equilibrium Temperature ◽  
Intrinsic Variability ◽  
Winter Solstice ◽  
Fluctuation Dissipation ◽  
Fluctuation Dissipation Theorem ◽  
Order Of Magnitude ◽  
Leading Mode ◽  
Set Up ◽  
Hemisphere Winter

Abstract In simple GCMs, the time scale associated with the persistence of one particular phase of the model’s leading mode of variability can often be unrealistically large. In a particularly extreme example, the time scale in the Polvani–Kushner model is about an order of magnitude larger than the observed atmosphere. From the fluctuation–dissipation theorem, one implication of these simple models is that responses are exaggerated, since such setups are overly sensitive to any external forcing. Although the model’s equilibrium temperature is set up to represent perpetual Southern Hemisphere winter solstice, it is found that the tropospheric eddy-driven jet has a preference for two distinct regions: the subtropics and midlatitudes. Because of this bimodality, the jet persists in one region for thousands of days before “switching” to another. As a result, the time scale associated with the intrinsic variability is unrealistic. In this paper, the authors systematically vary the model’s tropospheric equilibrium temperature profile, one configuration being identical to that of Polvani and Kushner. Modest changes to the tropospheric state to either side of the parameter space removed the bimodality in the zonal-mean zonal jet’s spatial distribution and significantly reduced the time scale associated with the model’s internal mode. Consequently, the tropospheric response to the same stratospheric forcing is significantly weaker than in the Polvani and Kushner case.

scholarly journals On the transient fluctuation dissipation theorem after a quench at a critical point

2015 ◽  
Vol 111 (4) ◽  
pp. 40013
Author(s):  
Isaac Theurkauff ◽  
Aude Caussarieu ◽  
Artyom Petrosyan ◽  
Sergio Ciliberto
Keyword(s):  
Critical Point ◽  
Fluctuation Dissipation ◽  
Fluctuation Dissipation Theorem

Modification of charge density wave fluctuations by charge perturbations

2002 ◽  
Vol 12 (9) ◽  
pp. 77-78
Author(s):  
S. N. Artemenko
Keyword(s):  
Electric Field ◽  
Linear Response ◽  
Chemical Potential ◽  
Density Wave ◽  
Mean Field ◽  
Phase Fluctuations ◽  
Fluctuation Dissipation ◽  
Fluctuation Dissipation Theorem ◽  
The Mean ◽  
Field Transition

Spectral density of fluctuations of the CDW phase are calculated taking into account electric field induced by phase fluctuations. The approach based upon the fluctuation-dissipation theorem (FDT) combined with equations of linear response of the CDW conductor is used. Fluctuating electric field is found to suppress fluctuations of the phase, while fluctuations of the electric potential are sizeable. This suggests that transition from the CDW to the normal state (which is usually observed well below the mean-field transition temperature) may he provoked by fluctuations of the chemical potential, rather than by destruction of the CDW coherence between conducting chains due to phase fluctuations.

scholarly journals Probing the Fluctuation-Dissipation Theorem in a Perrin-like Experiment

2011 ◽  
Vol 107 (13) ◽  
Author(s):  
Jean Colombani ◽  
Laure Petit ◽  
Christophe Ybert ◽  
Catherine Barentin
Keyword(s):  
Fluctuation Dissipation ◽  
Fluctuation Dissipation Theorem
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