Berlin 2018 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 120: Tribology: Surfaces and nanostructures
O 120.3: Vortrag
Freitag, 16. März 2018, 12:00–12:15, MA 144
Influence of phase transitions on nanoscale friction in the charge density wave material 1T-TaS2 — Torben Marx1, •Dirk Dietzel1, Emanuele Panizon2, Franco Pellegrini2, Giuseppe E. Santoro2,3,4, Erio Tosatti2,3,4, and Andre Schirmeisen1 — 1Institute of Applied Physics, Justus-Liebig-University Giessen, Giessen, Germany — 2International School for Advanced Studies (SISSA), Trieste, Italy — 3CNR-IOM Democritos National Laboratory, Trieste, Italy — 4The Abdus Salam International Centre for Theoretical Physics (ICTP), Trieste, Italy
In recent years, analyzing the temperature dependence of nanoscale friction has proven to be an instructive tool to pinpoint internal relaxation modes for materials like polymers [1] or self-assembled monolayers (SAM) [2]. Now, we will show, that friction force microscopy can also be applied to characterize phase transitions by detecting the accompanying mechanical anomalies. To do so, the lateral force signal was constantly monitored during a continuous change of the sample temperature. As a model system, we analyzed the charge density wave material 1T-TaS2 and found, that e.g. the first order phase transition between the NC-CDW and the C-CDW phase was accompanied by distinct friction peaks. This behavior can be explained by a theoretical model, where small mechanical perturbations by the AFM tip are assumed to preemptively trigger the spinodal transformation, if the free energy barrier preventing this transformation becomes small enough.
[1] Jansen et al., PRL 102, 236101 (2009)
[2] Marx et al., Langmuir 33, 6005 (2017)