Control parameter for the glass transition of glycerol evidenced by the static-field-induced nonlinear response

International audienceBy studying a nonlinear susceptibility on supercooled glycerol, we show that applying a static field E st increases the glass transition temperature T g by an amount quadratic in E st. This has important consequences: (i) it reinforces the relation between the two paths put forward in the last years to unveil the dynamical correlation volume close to T g ; (ii) it clarifies the interpretation of nonlinear measurements; (iii) it yields a new control parameter of the glass transition, which paves the way for experiments deepening our understanding of glasses

Evidence of Growing Spatial Correlations during the Aging of Glassy Glycerol

International audienceWe have measured, as a function of the age ta, the aging of the nonlinear dielectric susceptibility χ3 of glycerol below the glass transition. Whereas the linear susceptibility can be accurately accounted for in terms of an age dependent relaxation time τα(ta), this scaling breaks down for χ3, suggesting an increase of the amplitude of χ3. This is a strong indication that the number Ncorr of molecules involved in relaxation events increases with ta. For T = 0.96 × Tg, we find that Ncorr increases by ∼ 10% when ta varies from 1ks to 100ks. This sheds new light on the relation between length scales and time scales in glasses