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

• Published in: Europhysics letters Vol. 111; no. 4; pp. 40013 - p1-40013-p6
• Main Authors: Theurkauff, Isaac, Caussarieu, Aude, Petrosyan, Artyom, Ciliberto, Sergio
• Format: Journal Article
• Language: English
• Published: Les Ulis EDP Sciences, IOP Publishing and Società Italiana di Fisica 01.08.2015; IOP Publishing
• Subjects: 05.40.-a; 05.70.Jk; 64.60.-i; Aging (materials); Critical point; Dissipation; Dynamical systems; Dynamics; Electric fields; Fluctuation; Freedericksz transitions; Liquid crystals; Mathematical analysis; Phase transitions; Theorems
• ISSN: 0295-5075; 1286-4854
• DOI: 10.1209/0295-5075/111/40013

The Modified Fluctuation Dissipation Theorem (MFDT) proposed by G. Verley et al. (EPL, 93 (2011) 10002) for non-equilibrium transient states is experimentally studied. We apply MFDT to the transient relaxation dynamics of the director of a liquid crystal after a quench close to the critical point of the Fréedericksz Transition (FrTr), which has several properties of a second-order phase transition driven by an electric field. Although the standard Fluctuation Dissipation Theorem (FDT) is not satisfied, because the system is strongly out of equilibrium, the MFDT is perfectly verified during the transient in a system which is only partially described by a Landau-Ginzburg (LG) equation, to which our observations are compared. The results can be useful in the study of material aging.