Oberflächenstrukturen modulierter Systeme - Darstellung von regelmäßig angeordneten, polaren Nanodomänen mittels Piezoresponse Force Microscopy
Surface structures in modulated systems - Visualization of regularly arranged, polar nanodomains using piezoresponse force microscopy
by Claudia Kofahl
Date of Examination:2020-07-15
Date of issue:2020-07-23
Advisor:Prof. Dr. Götz Eckold
Referee:PD Dr. Helmut Klein
Referee:Dr. Heidrun Sowa
Referee:Prof. Dr. Burkhard Geil
Referee:Prof. Dr. Alec Wodtke
Referee:Prof. Dr. Nathalie Jun.-Kunkel
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Abstract
English
Piezo force microscopy has been used to visualize nanoscaled surface charge density waves in a modulated ferroelectric system for the first time. Those self-organized structures are found in incommensurate systems close to lock-in transition consisting of an ordered sequence of commensurate nanodomains separated by discommensurations. In ferroelectrics, these domains are antiparallel polarized. As a model system, K2ZnCl4 crystals doped with Rb2ZnCl4 is used where the nanodomain structure can be stabilized at room temperature. The surface kinetics was examined with this surface visualization system. The formation of so-called anti-stripples and the subsequent coarsening were observed.
Keywords: Surface structures; self-organized nanodomain; modulated systems; incommensurable phases; Piezoresponse Force Microscopy