Low Energy Singlets in the Excitation Spectrum of the Spin Tetrahedra System Cu_2Te_2O_5Br_2
arXiv:cond-mat/0111065 · doi:10.1016/S0022-3697(02)00056-2
Abstract
Low energy Raman scattering of the s=1/2 spin tetrahedra system Cu_2Te_2O_5Br_2 is dominated by an excitation at 18 cm^{-1} corresponding to an energy E_S=0.6Δ, with Δthe spin gap of the compound. For elevated temperatures this mode shows a soft mode-like decrease in energy pointing to an instability of the system. The isostructural reference system Cu_2Te_2O_5Cl_2 with a presumably larger inter-tetrahedra coupling does not show such a low energy mode. Instead its excitation spectrum and thermodynamic properties are compatible with long range Neel-ordering. We discuss the observed effects in the context of quantum fluctuations and competing ground states.
5 pages, 2 figures, ISSP-Kashiwa 2001, Conference on Correlated Electrons
References in corpus (2)
Cited by in corpus (5)
- Magnetic light scattering in low-dimensional quantum spin systems
- Longitudinal magnon in the tetrahedral spin system Cu2Te2O5Br2 near quantum criticality
- Investigation of the oxohalogenide Cu4Te5O12Cl4 with weakly coupled Cu(II) tetrahedra
- Magnetic Raman scattering of the ordered tetrahedral spin-1/2 clusters in Cu_2Te_2O_5(Br_(1-x)Cl_x)_2 compounds
- Anomalous frequency and intensity scaling of collective and local modes in a coupled spin tetrahedron system