Optical excitations in systems with frustrated lattice topology

光学和太赫兹光谱将在基于Cr的系统中进行，其中磁性Cr 3+离子占据几何阻挫晶格，特别是在反铁磁氧化物尖晶石ACr 2 O 4（A= Zn，Mg，Cd，Hg）的情况下的烧绿石晶格和A = Cu，Ag，Pd和X = O，S，Se的化合物ACrX 2的二维三角晶格。自旋和晶格自由度的耦合及其对提升磁基态的宏观简并度的影响，以及与经典自旋-液体区域中的有限自旋关联的关系将被探索。磁激发光谱将访问通过光学活性激子-磁振子跃迁和磁振子边带的寿命将调查相对于形成拓扑保护的Z2涡旋或六边形自旋分子的三角形和烧绿石化合物，分别。

Optical and THz spectroscopy will be performed in Cr based systems where the magnetic Cr3+ ions occupy geometrically frustrated lattices, in particular a pyrochlore lattice in the case of the antiferromagnetic oxide-spinels ACr2O4 (A= Zn, Mg, Cd, Hg) and a two-dimensional triangular lattice for compounds ACrX2 with A = Cu, Ag, Pd and X = O, S, Se. The coupling of spin and lattice degrees of freedom and its effects on lifting the macroscopic degeneracy of the magnetic ground state and the relation to the finite spin correlations in the classical spin-liquid regime will be explored. The magnetic excitation spectrum will be accessed via optically active exciton-magnon transitions and the lifetime of the magnon sidebands will be investigated with respect to the formation of topologically protected Z2 vortices or hexagonal spin-molecules in the triangular and pyrochlore compounds, respectively.