Dr. Falko Schmidt

Active Matter and Fluids Research

Fluctuation-driven forces in microcavities


Nowadays technologies, especially microelectronics, becomes increasingly powerful and complex by decreasing  the feature sizes down to a few nanometers. At such dimensions small forces can no longer be neglected but significantly influence device operation.

Vacuum fluctuations induce the well known Casimir force leading to irreversible stiction of metallic plates. In binary critical liquids, the analogous critical Casimir forces can be induced due to the density fluctuations (constant de- and remixing) occurring near-criticality.
Optical cavities formed between two boundaries in which light is being reflected multiple times before exiting can provide quantitative analysis of such forces. 
[Picture]
An optical cavity forms between a floating flake-like particles and its metallic substrate.

Publications


Nanoalignment by Critical Casimir Torques


Gan Wang, Piotr Nowakowski, Nima Farahmand Bafi, Benjamin Midtvedt, Falko Schmidt, Ruggero Verre, Mikael Käll, S. Dietrich, Svyatoslav Kondrat, Giovanni Volpe

Nature Communications, vol. 15(5086), 2024


Tunable critical Casimir forces counteract Casimir–Lifshitz attraction


Falko Schmidt, Agnese Callegari, Abdallah Daddi-Moussa-Ider, Battulga Munkhbat, Ruggero Verre, Timur Shegai, Mikael Käll, Hartmut Löwen, Andrea Gambassi, Giovanni Volpe

Nature Physics, 2022