Velocity tuning of friction with two trapped atoms

Abstract

Friction is the basic, ubiquitous mechanical interaction between two surfaces that results in resistance to motion and energy dissipation. In spite of its technological and economic significance, our ability to control friction remains modest, and our understanding of the microscopic processes incomplete 1-3 . At the atomic scale, mismatch between the two contacting crystal lattices can lead to a reduction of stick-slip friction (structural lubricity) 4-7 , while thermally activated atomic motion can give rise to a complex velocity dependence 8-14 , and nearly vanishing friction at sufficiently low velocities (thermal lubricity) 10,13 . Atomic force microscopy has provided a wealth of experimental results 6-9,14-19 , but limitations in the dynamic range, time resolution, and control at the single-atom level have hampered a full quantitative description from first principles 3 . Here, using an ion-crystal friction emulator with single-atom, single substrate-site spatial resolution and single-slip temporal resolution 5,20 , we measure the friction force over nearly five orders of magnitude in velocity, and contiguously observe four distinct regimes, while controlling temperature and dissipation. We elucidate the interplay between thermal and structural lubricity in a system of two coupled atoms, and provide a simple explanation in terms of the Peierls-Nabarro potential 21 . This extensive control at the atomic scale paves the way for fundamental studies of the interaction of many-atom surfaces, as for example in the Frenkel-Kontorova model 21 , and possibly into the quantum regime 22 .

Finite-temperature phase diagram and critical point of the Aubry pinned-sliding transition in a two-dimensional monolayer

“…[13][14][15][16] Real incommensurate lattices come into contact at an interface which is D = 2 dimensional. Moreover, temperature is always finite and often large.…”

Load-dependent destabilization of the γ-rotor shaft in F O F 1 ATP synthase revealed by hydrogen/deuterium-exchange mass spectrometry

“…In the following section, we make the case that such a model is consistent with our data. iv) Rotational resistance in the apical bearing: The movement of closely spaced protein surfaces relative to each other is accompanied by side-chain clashes and transient binding/ dissociation events (19), likely giving rise to intermittent motion in a stick-slip regime (18). MD simulations indicate that such friction-like effects are also encountered during rotation of the γ C-terminal helix within the α 3 β 3 apical bearing (15).…”

“…The irregular topologies and specific binding interactions of biomolecular interfaces complicate a rigorous discussion of dissipative effects in terms of classical friction models (18). It seems likely that sliding motions at such interfaces will be associated with resistance as individual residues clash with one another, and as transient binding interactions are formed and disrupted (19).…”

Current trends in the physics of nanoscale friction

“…Compared to standard experimental tribology techniques, another outstanding achievement within the framework of such ion-crystal system in a optical lattice relies on the possibility to span almost five orders of magnitude in velocity, while controlling temperature and dissipation [158], emulating the PT model to near perfection.…”