When: February 12, online 15:00

Avalanche Dynamics and Anisotropic Effects in Microscale Scratching of Molybdenum Disulfide

A clear understanding of friction and wear at small scales is essential to reduce energy dissipation in mechanical systems and mitigate environmental impact. In this context, two-dimensional transition metal dichalcogenides such as MoS₂ are of particular interest due to their potential as solid lubricants and next-generation nanoelectronic devices.

In this seminar, I will present a combined experimental and computational study of nanoscale wear and fracture in multilayer MoS₂. Atomic force microscopy experiments, performed by driving sharp diamond tips under loads inducing in-plane fracture, reveal a stick-slip regime responsible for the progressive exfoliation of compact MoS₂ chips. At high loads, slip events display signatures of avalanche dynamics at the nanoscale, with friction force drops following a Generalized Extreme Value distribution. Molecular dynamics simulations reproduce these trends and provide atomistic insight into the wear process, showing that only a small fraction of the injected mechanical energy leads to irreversible damage.

I will also discuss the strong crystallographic anisotropy of wear in MoS₂. Cutting along armchair and zigzag directions results in worn volumes differing by more than an order of magnitude, due to direction-dependent microcrack formation and chip detachment. These findings advance our understanding of fracture and energy dissipation in layered materials and offer guidelines for precision nanomachining of MoS₂-based devices.