2001/11/05 by P. Lemmens, K. Y. Choi, Kwang‐Yong Choi +14 · 3 citations
Materials Science · Physics and Astronomy · #Advanced Condensed Matter Physics #Magnetic and transport properties of perovskites and related materials #Physics of Superconductivity and Magnetism #cond-mat.mtrl-sci #cond-mat.str-el
paper · pdf · doi:10.1016/s0022-3697(02)00056-2
5 pages, 2 figures, ISSP-Kashiwa 2001, Conference on Correlated Electrons
arxiv created 2001/11/05 · openalex publication_date 2002/06/01 · arxiv updated 2009/11/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Low energy Raman scattering of the s=1/2 spin tetrahedra system Cu2Te2O5Br2 is dominated by an excitation at 18 cm-1 corresponding to an energy ES=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 Cu2Te2O5Cl2 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.