Inverse Layer Dependence of Friction on Re-doped MoS₂ Revealed by Atomic Force Microscopy

The possibility to tune the nanoscale frictional properties of two-dimensional (2D) materials via chemical doping is of considerable scientific and technological interest. Here, we present the results of atomic-force-microscopy-based friction measurements on Re-doped molybdenum disulfide (MoS₂) [arXiv:2007.05805]. In stark contrast to the seemingly universal observation of decreasing friction with increasing number of layers on 2D materials, friction on Re-doped MoS₂ exhibits an anomalous, i.e. inverse, dependency on the number of layers. Raman spectroscopy measurements reveal signatures of Re intercalation, providing clues regarding the physical mechanisms that result in this remarkable observation (see abstract of Strubbe et al.).