Controlling Exchange and Quenched Disorder in Low-Dimensional Spin Systems

• Applicant: Dr. Natalija van Well
• Subject Area: Experimental Condensed Matter Physics
• Term: from 2015 to 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 275299204

Investigation of structural and physical properties of new materials is the basis for the development of innovative products and technologies and therefore of high importance for the society as this knowledge produces an added value. Our rapidly evolving economy requires an even more systematic analysis of the physical properties of new materials to gain a sound understanding thereof in case of a modification of their composition. This allows enhancing technological ascendancy by specifically using such new findings for the development of new products. Therefore, research should not emphasis merely on the development of new materials, but on the understanding how to develop specific materials with pre-defined characteristics. Insights into the scheme of modification of physical properties are gained through synthesis and characterization of compositions and relations, elucidating the ordering mechanism, which determines the collective behavior of i.e. a correlated total system. Furthermore, as modeling of phases around quantum critical points are realizable through nonthermal control parameter, quenched disorder can lead to exotic critical points with interesting new properties. This research project Controlling Exchange and Quenched Disorder in Low-Dimensional Spin Systems focuses on the investigation of correlations by neutron scattering. It deals with the following three low-dimensional spin systems, designed and grown by the fellow at Goethe-University and which are very well suited for this research project: a) on the model-anisotropic triangular lattice material Cs2CuCl4-xBrx we study the effects of quenched disorder in quasi-one-dimensional frustrated systems; b) on the new metal-organic compound K(C8H16O4)2CuCl3 H2O we will investigate spin-correlations in interacting quantum dimer units, and c) in Ba1-xSrxCuSi2O6 we will explore the exciting physics of Bose-Einstein condensation at a two-dimensional quantum critical point.

• DFG Programme: Research Fellowships
• International Connection: Switzerland
• Host: Professor Dr. Christian Rüegg