Thermolubricity in atomic-scale friction

In this methods article, we describe application of Prandtl-Tomlinson models and their extensions to interpret dry atomic-scale friction. The goal is to provide a practical overview of how to use these models to study frictional phenomena. We begin with the fundamental equations and build on them step-by-step-from the simple quasistatic one-spring, one-mass model for predicting transitions between friction regimes to the two-dimensional and multi-atom models for describing the effect of contact area. The intention is to bridge the gap between theoretical analysis, numerical implementation, and predicted physical phenomena. In the process, we provide an introductory manual with example computer programs for newcomers to the field, and an illustration of the significant potential for this approach to yield new fundamental understanding of atomic-scale friction.

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“…If t v ) s, then the system is in the thermal drift regime where friction follows the prediction of Krylov et al [11,26,27],…”

Section: Thermal Activationmentioning

confidence: 84%

Analytical Models for Atomic Friction

2011

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“…In both these latter pictures for log rate dependence, there must be fluctuations (either of energy or of stress), which lead to logarithmic dependences of stress on shear rate because of activated processes described through Boltzmann factors. The atomic-scale friction community is actively exploring the details of such models (JINESH et al 2008).…”

Section: More Complex Behavior and Modelsmentioning

confidence: 99%

Stick–Slip and the Transition to Steady Sliding in a 2D Granular Medium and a Fixed Particle Lattice

Krim

Behringer

2011

Pure Appl. Geophys.

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We report an experimental study of the stick-slip to steady sliding behavior of a solid object pulled, via a spring, across 2D granular substrates of photoelastic disks that are either fixed in a solid lattice (granular solid) or unconstrained, forming a granular bed. We observe a progression of friction regimes with increasing sliding speed, including single-slip, double-slip, and mixed stickslip regimes, steady sliding, and inertial oscillations. For the case of the granular bed, we report a detailed analysis of frictional behavior for the low speed stick-slip regime, including spring and elastic energy dependencies during the stick and slip portions of the motion. For the case of the granular solid, we explore friction in the presence and absence of externally applied vibrations, and compare it with sliding on a granular bed, which is intrinsically disordered. We observe that external vibration reduces transition values for both the single-slip to double-slip transition and the stick-slip to steady sliding transition. Moreover, we observe that the effect of packing disorder on granular friction seems similar to the effect of vibration-induced disorder, a result that, to our knowledge, has not been reported previously in the experimental literature.

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“…This discrepancy is the signature of another dynamical rate of the system, the thermal hopping rate γ th ¼ 10 3 s −1 , observed previously in Refs. [30,45,46]. Thermal hopping across a barrier due to the ion's finite temperature dominates at the slowest transport speed, where v=a ∼ γ th (the thermolubric regime [30]).…”

Section: Figmentioning

confidence: 99%

Multislip Friction with a Single Ion

et al. 2017

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A trapped ion transported along a periodic potential is studied as a paradigmatic nanocontact frictional interface. The combination of the periodic corrugation potential and a harmonic trapping potential creates a one-dimensional energy landscape with multiple local minima, corresponding to multistable stick-slip friction. We measure the probabilities of slipping to the various minima for various corrugations and transport velocities. The observed probabilities show that the multislip regime can be reached dynamically at smaller corrugations than would be possible statically, and can be described by an equilibrium Boltzmann model. While a clear microscopic signature of multislip behavior is observed for the ion motion, the frictional force and dissipation are only weakly affected by the transition to multistable potentials. DOI: 10.1103/PhysRevLett.119.043601 Stick-slip friction is a ubiquitous nonequilibrium dynamical process that occurs at the interface between surfaces across a wide range of length scales [1][2][3][4][5][6]. The term stick slip describes the system's response to an applied shear force: the surfaces slip out of a local minimum in the interface energy landscape, and stick into a new lowerenergy minimum, releasing heat in the process.Recent advances in atomic force microscopy (AFM) have extended the study of stick-slip friction to the atomic scale, where atom-by-atom slips occur at the interface between a probe tip and a periodic substrate [7][8][9][10][11][12][13][14][15][16][17][18]. For a single-atom probe, the number of local minima in the probe-substrate interaction potential is determined by the ratio of the periodic substrate potential to the spring constant with which the probe is bound to its support object. As the load on the probe is increased, or equivalently, the periodic substrate potential is deepened, the system transitions from a bistable regime (where the probe deterministically single slips from the first minimum to the second) to a multistable regime (where a probe can stochastically multislip to one of several local minima). This has been demonstrated in AFM simulations [19][20][21][22] and experiments [23][24][25] where single-slip and multislip events have been clearly differentiated. However, in the absence of control over dissipation rates and the microscopic energy landscape, it is difficult to tie the observations to ab initio friction models.Following theoretical proposals [26][27][28][29], we have recently demonstrated a trapped-ion friction emulator with extensive control over all microscopic interface parameters [30][31][32]. In analogy to AFM, the emulator features a small probe (one or several trapped ions) transported over a In this Letter, we study multislip friction in deep substrate potentials. We observe the ion fluorescence associated with slip events, from which we directly extract the temperature-and velocity-dependent probabilities for the ion to localize in one of the available local minima. We find that at finite rethermalization times following a s...

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Thermolubricity in atomic-scale friction

Cited by 75 publications

References 24 publications

Analytical Models for Atomic Friction

Analytical Models for Atomic Friction

Stick–Slip and the Transition to Steady Sliding in a 2D Granular Medium and a Fixed Particle Lattice

Multislip Friction with a Single Ion

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