arXiv subjects

Ch. Rüegg

Publications and source records attributed to Ch. Rüegg.

38 records · Page 3Linked to original sources

arXiv2006

Multiple Magnon Modes and Consequences for the Bose-Einstein Condensed Phase in BaCuSi2O6

The compound BaCuSi2O6 is a quantum magnet with antiferromagnetic dimers of S = 1/2 moments on a quasi-2D square lattice. We have investigated its spin dynamics by inelastic neutron scattering experiments on single crystals with an energy resolution considerably higher than in an earlier study. We observe multiple magnon modes, indicating clearly the presence of magnetically inequivalent dimer sites. This more complex spin Hamiltonian leads to a distinct form of magnon Bose-Einstein condensate (BEC) phase with a spatially modulated condensate amplitude.

cond-mat.str-el↗

arXiv2005

Quantum Statistics of Interacting Dimer Spin Systems

The compound TlCuCl3 represents a model system of dimerized quantum spins with strong interdimer interactions. We investigate the triplet dispersion as a function of temperature by inelastic neutron scattering experiments on single crystals. By comparison with a number of theoretical approaches we demonstrate that the description of Troyer, Tsunetsugu, and Wuertz [Phys. Rev. B 50, 13515 (1994)] provides an appropriate quantum statistical model for dimer spin systems at finite temperatures, where many-body correlations become particularly important.

cond-mat.str-el↗