RESUMO
Continuous spin excitations are widely recognized as one of the hallmarks of novel spin states in quantum magnets, such as quantum spin liquids (QSLs). Here, we report the observation of such kind of excitations in K_{2}Ni_{2}(SO_{4})_{3}, which consists of two sets of intersected spin-1 (Ni^{2+}) trillium lattices. Our inelastic neutron scattering measurement on single crystals clearly shows a dominant excitation continuum, which exhibits a distinct temperature-dependent behavior from that of spin waves, and is rooted in strong quantum spin fluctuations. Further using the self-consistent-Gaussian-approximation method, we determine that the fourth- and fifth-nearest-neighbor exchange interactions are dominant. These two bonds together form a unique three-dimensional network of corner-sharing tetrahedra, which we name as a "hypertrillium" lattice. Our results provide direct evidence for the existence of QSL features in K_{2}Ni_{2}(SO_{4})_{3} and highlight the potential for the hypertrillium lattice to host frustrated quantum magnetism.
RESUMO
The results of the structural determination, magnetic characterization, and theoretical calculations of a new ruthenium-oxo complex, Li4[Ru2OCl10]·10H2O, are presented. Single crystals were grown using solvent methods and the crystal structure was characterized by single crystal X-ray diffraction. Li4[Ru2OCl10]·10H2O crystallizes into a low-symmetry triclinic structure (P1) due to the much smaller Li+ cation compared to K+ cation in the tetragonal complex K4[Ru2OCl10]·H2O. The X-ray photoelectron spectra confirm only the single valent Ru4+ in Li4[Ru2OCl10]·10H2O even though two distinct Ru sites exist in the crystal structure. Magnetic measurements reveal the diamagnetic property of Li4[Ru2OCl10]·10H2O with unpaired electrons existing on Ru4+. Furthermore, the molecular orbital analysis matches well with the observed UV and magnetic measurements.
