Predictions and Observations of Multiple Slip Modes in Atomic-Scale Friction

Using the quasistatic Tomlinson model as a simple representation of an atomic force microscope, conditions for transitions in atomic-scale friction behavior from smooth sliding to single slips and then multiple slip regimes are derived based on energy minimization. The calculations predict and give a general explanation for transitions between different stick-slip regimes in the limit of low damping. The predictions are consistent with experimental observations of these transitions.

Figure 1

(a) System configuration and periodic potential field. (b) Tip-substrate interaction force $F_{\mathrm{lat}}$ and spring forces $F_i$ ($i=1,\dots ,4$) corresponding to the critical stiffness values.

Figure 2

Relationship between $j_0(z)$ and critical values $k_i^{\prime }$.

Figure 3

Energy landscapes. $E_i$ correspond to $k_i$, $i=1,\dots ,5$.

Figure 4

Stick-slip opportunity map. Theoretical predictions.

Figure 5

Stick-slip friction map. Experimental results.

Figure 6

Representative experimental friction behavior with increasing load (offset for clarity). Lateral force vs position traces demonstrate transitions from smooth sliding (top) to single (middle) and mostly double slips (bottom).