|演 題||「Polarons Imaged in Real Space by Combined AFM/STM」|
|日 時||2022年11月28日(月) 17:00|
|講演者||Prof. Martin Setvin (Charles University, Czech Republic)|
Polarons  are quasiparticles that form in ionic lattices due to the interaction of excess charges with lattice distortions. This leads to a spatial confinement of the charge and appearance of many novel phenomena. In past decades, polarons turned out to play an important role in electrical transport, optical properties, organic electronics, catalysis, or in exotic materials properties such as colossal magnetoresistance or high-Tc superconductivity.
I will discuss options of studying the polaron properties by scanning probe methods. First, traces of small and large polarons in Scanning tunnelling spectroscopy will be discussed on the prototypical example of TiO2 rutile and anatase . The use of atomic force microscopy brings an option of imaging and manipulating single small polarons; this will be illustrated on examples of hematite Fe2O3 and the KTaO3 perovskite. Last, the options of studying electron transfer between a solid substrate and adsorbed molecules will be illustrated on several systems: CO adsorbed on Rutile TiO2 , CO adsorbed on cleaved KTaO3  and O2 adsorbed on anatase TiO2 . Each case carries distinctly different characteristics for transferring the electron and requires a choice of an appropriate analysis method.
 Franchini, C., Reticcioli, M., Setvin, M. & Diebold, U. Polarons in Materials. Nature Reviews Materials 6, 560-586 (2021).