The sliding motion of objects is typically governed by their friction with the underlying surface. Compared to translational friction, however, rotational friction has received much less attention. Here, we experimentally and theoretically study the rotational depinning and orientational dynamics of twodimensional colloidal crystalline clusters on periodically corrugated surfaces in the presence of magnetically exerted torques. We demonstrate that the traversing of locally commensurate areas of the moire??pattern through the edges of clusters, which is hindered by potential barriers during cluster rotation, controls its rotational depinning. The experimentally measured depinning thresholds as a function of cluster size strikingly collapse onto a universal theoretical curve which predicts the possibility of a superlow-statictorque state for large clusters. We further reveal a cluster-size-independent rotation-translation depinning transition when lattice-matched clusters are driven jointly by a torque and a force. Our work provides guidelines to the design of nanomechanical devices that involve rotational motions on atomic surfaces.

Moiré-Pattern Evolution Couples Rotational and Translational Friction at Crystalline Interfaces / X. Cao, A. Silva, E. Panizon, A. Vanossi, N. Manini, E. Tosatti, C. Bechinger. - In: PHYSICAL REVIEW. X. - ISSN 2160-3308. - 12:2(2022 Jun 15), pp. 021059.1-021059.14. [10.1103/PhysRevX.12.021059]

Moiré-Pattern Evolution Couples Rotational and Translational Friction at Crystalline Interfaces

N. Manini;
2022

Abstract

The sliding motion of objects is typically governed by their friction with the underlying surface. Compared to translational friction, however, rotational friction has received much less attention. Here, we experimentally and theoretically study the rotational depinning and orientational dynamics of twodimensional colloidal crystalline clusters on periodically corrugated surfaces in the presence of magnetically exerted torques. We demonstrate that the traversing of locally commensurate areas of the moire??pattern through the edges of clusters, which is hindered by potential barriers during cluster rotation, controls its rotational depinning. The experimentally measured depinning thresholds as a function of cluster size strikingly collapse onto a universal theoretical curve which predicts the possibility of a superlow-statictorque state for large clusters. We further reveal a cluster-size-independent rotation-translation depinning transition when lattice-matched clusters are driven jointly by a torque and a force. Our work provides guidelines to the design of nanomechanical devices that involve rotational motions on atomic surfaces.
rotational friction; atomic-scale friction; colloids
Settore FIS/03 - Fisica della Materia
PRIN201719NMANI_01 - Understanding and Tuning FRiction through nanOstructure Manipulation (UTFROM) - MANINI, NICOLA - PRIN2017 - PRIN bando 2017 - 2019
https://journals.aps.org/prx/abstract/10.1103/PhysRevX.12.021059
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/935308
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