Prof. Martin Setvin

Charles University, Czechia
Martin Setvin obtained his PhD in 2012 at Charles University in Prague in the field of Surface Physics. Later he spent 8 years in Vienna, focusing on the surfaces of metal oxides and development of the combined scanning tunnelling microscopy and noncontact atomic force microscopy. In 2020 he assumed an associate professor position at Charles University in Prague and set up his own research group there.

Talk title: Imaging and tracking polarons in Fe₂O₃ and SrTiO₃ by atomic force microscopy
Noncontact atomic force microscopy (nc-AFM) has recently proven to be a powerful tool for manipulating and imaging single electrons at surfaces. Single electrons could be localized at trapping sites such as Au atoms on thin NaCl films [1], small molecules on oxide surfaces [2], or larger organic molecules on thicker NaCl films [3].

This talk will focus on the possibilities of investigating polarons in materials: Polarons are electrons or holes that self-localize in ionic lattices due to electron-phonon interaction [4]. Such charge carriers can move to adjacent lattice positions, provided they are given certain activation energy. Polarons play a key role in many applications and materials properties, such as electrical conductivity, optical properties, catalysis and photocatalysis, and they stand behind exotic properties such as colossal magnetoresistance or high-temperature superconductivity. The successful imaging of polarons in hematite Fe₂O₃ and SrTiO₃ will be shown, and the new possibilities offered by this technique will be discussed.
The work was supported by projects MSMT CZ.02.01.01/00/22_008/0004572 and LL2324.
[1]     L. Gross et al., Science 324, 1428 (2009)
[2]     M. Setvin et al., PNAS 114, E2556 (2017)
[3]     S. Fatayer et al., Science 365, 142 (2019)
[4]     C. Franchini et al., Nature Reviews Materials 6, 560 (2021)