Understanding and controlling self-organized stripe pattern formation in vanadium dioxide

• Applicant: Dr. Jon-Olaf Krisponeit
• Subject Area: Experimental Condensed Matter Physics ; Synthesis and Properties of Functional Materials
• Term: from 2018 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 408002857

The ongoing rapid exploration of oxide materials has led to the discovery of effects as spectacular as interface superconductivity, magnetoresistance, and electrical switching phenomena. This has opened up the technological perspective of oxide electronics and spintronics. Here, in addition to the development of conventional device types inherited from silicon-based predecessors, entirely novel functional elements have been created. However, not only the functional materials themselves but also the interfacial properties and the costly preparation of complex heterostructures on the scale of single atomic layers are of vital importance. Vanadium dioxide (VO2) is a functional material with a tremendous technological potential due to an metal-insulator transition close to room temperature. This project addresses strain relaxation mechanisms in VO2 under epitaxial strain, which can lead to complex phase separation phenomena like the self-organized formation of stripe patterns consisting of metallic and insulating regions and hence yield intrinsic interfaces. Further, the project is dedicated to the question to what extent an alternative route to complex heterostructures can be obtained from these effects. Starting from the strain-dependent formation of self-assembled stripe patterns in a complex oxide, these stripe patterns are investigated on a microscopic scale to gain fundamental insights in their physical properties. The focus lies on the influences of the geometric shape on the stability of such stripe patterns and on their structural and electrical properties and their manipulation.In particular, this project aims for the first implementation of entirely new device concepts in oxide electronics. Here, the emergence of intrinsic interfaces is controlled specifically by geometric functionalization: the device functionality arises from the subsequent manipulation of such interfaces by external electric fields. A combination of modern, complementary microscopy techniques and targeted structuring on the micrometer to nanometer scale is used to simultaneously obtain insights in the electronic and structural properties of correlated oxides and develop innovative functional elements for applications in future oxide electronics.

• DFG Programme: Research Grants