On relaxations and aging of various glasses

Abstract

Slow relaxation occurs in many physical and biological systems. "Creep" is an example from everyday life. When stretching a rubber band, for example, the recovery to its equilibrium length is not, as one might think, exponential: The relaxation is slow, in many cases logarithmic, and can still be observed after many hours. The form of the relaxation also depends on the duration of the stretching, the "waiting time." This ubiquitous phenomenon is called aging, and is abundant both in natural and technological applications. Here, we suggest a general mechanism for slow relaxations and aging, which predicts logarithmic relaxations, and a particular aging dependence on the waiting time. We demonstrate the generality of the approach by comparing our predictions to experimental data on a diverse range of physical phenomena, from conductance in granular metals to disordered insulators and dirty semiconductors, to the low temperature dielectric properties of glasses.nonequilibrium | slow dynamics | memory effects | 1/f noise P hysicists often take for granted that systems relax exponentially. Indeed, when a capacitor discharges, it will discharge exponentially, with a rate independent of the time it has been charged for. However, the relaxation of many systems in nature is far from exponential, as was noticed already in the 19th century by Weber (1). In many cases, the relaxation is logarithmic: Such relaxations have been experimentally observed in the decay of current in superconductors (2), current relaxation in metal-oxidesemiconductor field-effect transistor devices (3), mechanical relaxation of plant roots (4), volume relaxation of crumpling paper (5), and frictional strength (6), to name but a few. Fig. 1 shows experimental data for electron glasses and for crumpling a thin sheet, which are governed by extremely different physical processes, yet they display identical relaxation behavior, which is logarithmic over a strikingly broad time window.In these systems, in contrast to the capacitor example, the relaxation does depend on the time the system has been perturbed for-in the scientific jargon, this is referred to as "aging." In fact, slow relaxations and aging are amongst the most distinct features of glasses, whose understanding presents an important problem in contemporary condensed matter physics. Much experimental and theoretical attention has been devoted to aging in the past decades, in a variety of fields, such as spin-glass (7-13), colloids (14, 15), vortices in superconductors (16,17), and many others (18-23).Here, we study a generic model for aging and discuss several mechanisms yielding a broad distribution of relaxation rates. We demonstrate the generality of the model on four different experimental systems, measuring the dependence of the relaxation both on time t and on the "waiting time" t w , during which an external perturbation has been applied. We show how the following form of relaxations transpires: Sðt;t w Þ ∝ logð1 þ t w ∕tÞ ¼ logðt w ∕tÞ for t ≪ t w ; t w ∕t for t ≫ t w ;where S is the p...

Comparing the mechanism of water condensation and evaporation in glassy aerosol

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Controllable quantum spin glasses with magnetic impurities embedded in quantum solids

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Relaxation dynamics of Fe55Cr10Mo14C15B6 metallic glass explored by mechanical spectroscopy and calorimetry measurements

“…Mechanical 17 spectroscopy, by applying a periodic excitation and analyzing the phase lag between the stimuli and 18 response, has been proven to be an effective method for exploring the dynamics of glassy systems [23-19 27]. The relaxation dynamics in metallic glasses has attracted great attention recently [1,24,[28][29][30][31]. 20…”

“…Fe-based metallic glasses (MGs) show some unique properties [1][2][3]; due to their low coercivity and 19 high permeability, combined with a high electrical resistivity which is helpful for reducing eddy current 20 losses, soft magnetic MGs are widely used in laminated transformer cores [4][5][6]. Besides, due to the 21 relatively cheap raw materials, acceptable glass forming ability (GFA), good corrosion resistance and 22 high elastic strength, they are promising as structural engineering materials [6][7][8][9].…”

“…In order to describe the low temperature peak, here we will assume that it is a thermal activated 14 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 as obtained by calorimetry, the activation energy of the Johari-Goldstein relaxation would be around 9 171 kJ mol - 1 . The activation energy of the low temperature relaxation determined here is thus close to 10 the value expected for Johari-Goldstein relaxations in metallic glasses; however, with only the 11 activation energy it is difficult to tell whether the secondary relaxation is a JG-relaxation or not.…”