Lattice anomalies and magnetic excitations of the spin web compound Cu ₃TeO₆

We report on the magnetic susceptibility and Raman scattering measurements of the S = 1/2 three-dimensional (3D) spin web compound Cu₃TeO ₆. The magnetic susceptibility shows an antiferromagnetic ordering at T_N∼61K and a deviation from the Curie-Weiss law around 150K. Raman spectra show the emergence of a new mode at 132cm^-1 for temperatures below T^*∼50K (≈0.8T_N). At the same temperature, phonon anomalies in intensity and frequency show up. This gives evidence of pronounced magneto-elastic effects. In addition, we observe a two-magnon Raman spectrum around 214cm^-1. Compared to typical 3D spin systems, its robust temperature dependence suggests that a frustrated spin topology with a reduced spin coordination number also enhances spin-phonon couplings.