Atomic Friction: Anisotropy and Asymmetry Effects

Fessler, Gregor; Sadeghi, Ali; Glatzel, Thilo; Goedecker, Stefan; Meyer, Ernst

doi:10.1007/s11249-019-1172-9

Cited by 13 publications

(10 citation statements)

References 31 publications

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“…The COM trajectory shows that the tip does not move directly along the direction of pulling but instead meanders across the surface, as previously reported for previous AFM experiments. [38][39][40] This behavior can be attributed to the spring compliance both along the axis of sliding and the axis perpendicular to sliding, which enables the tip to follow a lower energy path. In addition, high frequency fluctuations in response to both thermal noise and the varying tip-sample forces occur due to the dynamic responses of these springs.…”

Section: Resultsmentioning

confidence: 99%

Nanoscale Friction Behavior of Transition-Metal Dichalcogenides: Role of the Chalcogenide

et al. 2020

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Despite extensive research on the tribological properties of MoS2, the frictional characteristics of other members of the transition metal dichalcogenide (TMD) family have remained relatively unexplored. To understand the effect of the chalcogen on the tribological behavior of these materials and gain broader general insights into factors controlling friction at the nanoscale, we compared the friction force behavior for a nanoscale single asperity sliding on MoS2, MoSe2, and MoTe2 in both bulk and monolayer forms through a combination of atomic force microscopy (AFM) experiments and molecular dynamics (MD) simulations. Experiments and simulations showed that, under otherwise identical conditions, MoS2 has the highest friction among these materials and MoTe2 the lowest. Simulations complemented by theoretical analysis based on the Prandtl-Tomlinson model revealed that the observed friction contrast between theTMDs was attributable to their lattice constants, which differed depending on the chalcogen. While the corrugation amplitudes of the energy landscapes are similar for all three materials, larger lattice constants permit the tip to slide more easily across correspondingly wider saddle points in the potential energy landscape. These results emphasize the critical role of the lattice constant, which can be the determining factor for frictional behavior at the nanoscale.

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Section: Resultsmentioning

confidence: 99%

Nanoscale Friction Behavior of Transition-Metal Dichalcogenides: Role of the Chalcogenide

et al. 2020

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“…Measuring friction anisotropy requires the ability to either rotate the sample with respect to the cantilever scanning direction (see Figure S1a) via a specially designed stage as done, e.g., in Ref. 20, or a method to calibrate forces and pull the AFM tip along different scanning directions as done, e.g., in Ref. 21 (see Figure S1b).…”

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confidence: 99%

“…Recent theoretical and experimental studies 20,47,48 suggest that the interaction potential at the contact interface affects the configuration of anisotropic frictional forces. Therefore, if the potential energy landscape exhibits anisotropy, this could directly explain the observed friction trends.…”

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confidence: 99%

Friction Anisotropy of MoS₂: Effect of Tip–Sample Contact Quality

Vazirisereshk

Hasz

Carpick

et al. 2020

J. Phys. Chem. Lett.

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Atomic-scale friction measured for asperities sliding on 2D materials depend on the direction of scanning relative to the material's crystal lattice. Here, nanoscale friction anisotropy of wrinkle-free bulk and monolayer MoS2 is characterized using atomic force microscopy and molecular dynamics simulations. Both techniques show 180 o periodicity (twofold symmetry) of atomic-lattice stick-slip friction vs. the tip's scanning direction with respect to the MoS2 surface. The 60 o periodicity (six-fold symmetry) expected from the MoS2 surface's symmetry is only recovered in simulations where the sample is rotated, as opposed to the scanning direction changed. All observations are explained by the potential energy landscape of the tip

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“…Based on the above, the presence of the solvent appears to affect the effective contact stiffness through the applied load (in addition to the known impact of the load on the amplitude of the interaction energy). We chose to focus on data that were collected at room temperature, at a single constant scanning velocity, such that the amplitude of the corrugation interaction potential and the effective stiffness can be affected by effects of symmetry and dimensionality [13,[25][26][27][30][31][32][33] through the applied normal load [26,33,42,43]. Consequently, the 1D interpretation of 2D motion of the tip, or some deviation from the symmetry of the sine periodic interaction energy ascribed by the PT model, can potentially influence the behaviors of U 0 and K eff .…”

Section: Resultsmentioning

confidence: 99%

“…During a scan, the tip bends and releases with respect to its position along the atomic-scale periodicity of the sample (for ordered surfaces), and produces a stick-slip pattern in the lateral force signal. Studies on nanoscale friction have shown that several properties influence this dynamics, such as contact area [4][5][6][7][8][9], sliding velocity [10][11][12][13][14][15][16], temperature [11,[17][18][19][20][21][22][23], anisotropy, symmetry and dimensionality [13,[24][25][26][27][28][29][30][31][32][33], and the applied normal load [4,5,23,26,[33][34][35][36][37][38][39][40][41][42][43].…”

Section: Introductionmentioning

confidence: 99%

Comparative Study of Dimensionality and Symmetry Breaking on Nanoscale Friction in the Prandtl–Tomlinson Model with Varying Effective Stiffness

2020

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Friction Force Microscopy (FFM) measurements on NaCl immersed in ethanol display an increase of the effective contact stiffness with the applied load. This stiffness is estimated from the measured local contact interaction of the tip with the NaCl surface and the Prandtl-Tomlinson (PT) parameter, which reflects the relation between the corrugation stiffness and the effective contact stiffness. Different from FFM measurements in ultrahigh vacuum, for measurements in ethanol surroundings the PT parameters showed a maximum with the applied load. We incorporated this measured load-dependent effective stiffness together with the load-dependent amplitude of the corrugation energy into simulations based on the PT model, and studied its effect on the lateral friction for symmetric 1D and 2D potentials, as well as for an asymmetric 1D potentials. The simulations reproduced the experimentally observed non-monotonous behavior of the PT parameter, and enabled a glimpse on the relation of the characteristic observables (mean maximal slip forces and stiffness) with respect to their governing parameters (corrugation energy, effective stiffness). In all, apart from large deviations from symmetry in the interaction potential, the PT parameter provides a reliable estimate for nanoscale friction over periodic surfaces.

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Atomic Friction: Anisotropy and Asymmetry Effects

Cited by 13 publications

References 31 publications

Nanoscale Friction Behavior of Transition-Metal Dichalcogenides: Role of the Chalcogenide

Nanoscale Friction Behavior of Transition-Metal Dichalcogenides: Role of the Chalcogenide

Friction Anisotropy of MoS₂: Effect of Tip–Sample Contact Quality

Comparative Study of Dimensionality and Symmetry Breaking on Nanoscale Friction in the Prandtl–Tomlinson Model with Varying Effective Stiffness

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Atomic Friction: Anisotropy and Asymmetry Effects

Cited by 13 publications

References 31 publications

Nanoscale Friction Behavior of Transition-Metal Dichalcogenides: Role of the Chalcogenide

Nanoscale Friction Behavior of Transition-Metal Dichalcogenides: Role of the Chalcogenide

Friction Anisotropy of MoS2: Effect of Tip–Sample Contact Quality

Comparative Study of Dimensionality and Symmetry Breaking on Nanoscale Friction in the Prandtl–Tomlinson Model with Varying Effective Stiffness

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Friction Anisotropy of MoS₂: Effect of Tip–Sample Contact Quality