[2P01-29] Poster session

[2P06] Stability theory for scan-path-dependent stick-slip transitions and slip directions in AFM

*Shun Seo¹, Naruo Sasaki¹ (1. Department of Engineering Science, The University of Electro-Communications (Japan))

Nanoscale stick-slip friction in atomic-force microscopy can be understood as a mechanical instability of a tip moving on a corrugated surface potential. Although this transition has often been discussed using the Tomlinson model and the dimensionless parameter η, the scan-path dependence of both the transition boundary and the slip angle has not yet been described within a single stability framework. We develop a Hessian-based theory for a three-dimensional Tomlinson model with a honeycomb surface potential. The stick-slip transition occurs when the minimum eigenvalue of the Hessian matrix vanishes. The same eigenvalue problem determines the scan-path-dependent critical parameter η_c(θ,Y_s⁰) and the corresponding instability eigenvector, from which the slip angle φ is obtained. The theory quantitatively agrees with quasistatic simulations and shows that the transition boundary is directly linked to slip directionality. This behavior reflects competition between scan-directional slip and slip along high-symmetry directions. The formulation can be extended to other surface potentials and lattice symmetries.

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