Abstract
Cu3TeO6 is a modest frustrated S = 1/2 spin system, which undergoes an antiferromagnetic transition at TN ∼ 63 K. The antiferromagnetic spin alignment in Cu3TeO6 below TN is supposed to induce a magneto-elastic strain of the lattice. The complete absorption spectrum of Cu3TeO6 is obtained through Kramers-Kronig transformation of the optical reflectivity, measured from the far-infrared up to the ultraviolet spectral range as a function of temperature (T). Below T* ∼ 50 K, we find a new mode at 208 cm−1. The spectral weight associated to this additional mode increases as ∝ (T* − T)1/2 with decreasing T below T*. The implication of the optical findings will be discussed in relation to the magnetic phase transition at TN.