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Die Arbeit beschäftigt sich mit der Herstellung sowie der strukturellen und magnetischen Charakterisierung von zwei Materialklassen von kupferbasierten zweidimensionalen Quanten-Spin-Systemen: Quadratische Gitter von Dimeren sowie geometrisch frustrierte Kagomé Gitter. In beiden Systemen werden Substitutionen vorgestellt die zu verbesserten Eigenschaften führen.
Due to the small photon momentum, optical spectroscopy commonly probes magnetic excitations only at the center of the Brillouin zone; however, there are ways to override this restriction. In case of the distorted kagome quantum magnet Y-kapellasite, Y3Cu9(OH)19Cl8, under scrutiny here, the spin (magnon) density of states (SDOS) can be accessed over the entire Brillouin zone through three-center magnon excitations. This mechanism is aided by the three different magnetic sublattices and strong short-range correlations in the distorted kagome lattice. The results of THz time-domain experiments agree remarkably well with linear spin-wave theory (LSWT). Relaxing the conventional zone-center constraint of photons gives a new aspect to probe magnetism in matter.